Without quoting multiple people, here are my 2 cents. There may be 40-45% android users but a very little percentage of that can/do pay. I'll tell you why. Most Android users are from third world or developing countries. Have you ever seen any Celebrities, Instagram models or even remotely known person from any of the developed countries holding an Android device? No. They all brandish the latest IPhone. If there are charts for Android vs iOS users in US or other developed countries then that can be relevant here. Bottom line is, even if all Devs release an Android port of their games with every release, they won't generate 40-45% extra revenue. It'll be far far less. If they already have an iOS version then they are not missing that much.
Google does not allow any adult game/app on their store so a Dev can't sell their game in legit way like steam for Windows. That being said, google does allow to install any apk file so there's no bar in installing anything as long as it matches .apk format. I don't know about all game engines but I've tried only Renpy and even that is quite complex to port. And even after porting by following all steps, additional tweaks need to be performed. Like someone said, it's not worth the hassle. So far I've seen mostly Renpy based VNs get ported. Those seem to be easiest to do. Even non-vn sandbox/point and click style Renpy games don't get a port a lot of times as I've noticed. Again it comes to complexity, time and willingness.
Android downloads are not only 20%. It can't be. It will be almost 50-50%. First of all, there are multiple porters with different links to different filehosters(most use mega). I follow some of them. Some also have their own sites, blogs outside F95ZONE. A lot of people directly download from there and don't even visit this site. I know this cause I do that most of the time and I see a huge traffic on those sites. These are people who have given up on seeing a new game/update on this site and then waiting for days/weeks/months and never getting an android port. So they just play whatever new game/update gets an android port elsewhere. But as someone mentioned that it's impossible for porters to port all these games. Most of them do it cause they like it or just for fun in their free time. Some try making money with blogs and ads; those are annoying but necessary. A porter I know recently got hired by a Dev of a big name game here to officially port that game. I think every Dev should do this if they are not porting themselves. If it is too complex/time waster for you then just hire someone. You owe these unofficial porters something because of the extra publicity/traffic they bring to your games. That's just my thought.
Now something that might be a bit off-topic here but I think I should give a context to my first paragraph. I'm from a third world country and no; most Android users don't also own a PC here. I think it may be hard to grasp but it's the truth. Also sitting in front of a big tv on your couch with a wireless mouse to play a porn game? That kind of privacy is out of the question in countries like mine. Most of the time there's always someone where the computer is or someone else wanting to use it (if you have a computer in the first place). Using a handheld device when everyone in the house has fallen asleep is the only way. You may be thinking about only school or college students but no. Even grown ups with jobs have to live with their parents and maybe with their siblings and their own families too in a same house. That's the kind of deal you get when you live in a third world country. You can't just move out and live alone or with your own family either. I won't go any further into it cause I know how hard it is to understand for someone living in USA or other 1st world countries. But that is the gist of it for an Android user from a poor country.
So that's my final take on this subject. Android is poor man's device. But as this is a pirate site and even though most devs, moderators or active members are probably from one developed country or other(I said most); Out of the 5million members(A big chunk of it can be fake, dead accounts), more than 3/4th are possibly just pirates who will never pay/support a porn game AND a lot of them mostly use Android. So why bother making an extra effort for them. I say it ironically of course. A little rambling to conclude this: I once was in DPC's BADIK reddit fan group. It's so toxic with people who admonish pirates. A high tier supporter once said that DPC doesn't like f95zone either even though he started right here. Then he(that guy,not DPC) went on a rant about how it should be of no consequence for everybody to give at least $10 for every update even if someone does not stay subscribed and pay every month. Said it was just the cost of a burger or the expense of a one time snack. I told him that I agree completely. Then I told him that when I was in college in mid 2010s, that $10 equivalent used to cover my meal expense for an entire month; that includes any and all snacks. Right now that number has almost doubled but still you can see the distinction.
So to all Devs, if you make Android ports of your games out of the seer goodness of your heart then you deserve a pat on the back. If not then at least contract a porter to do it for you. Most Android users may not be able to pay right now but they might at some point in the future; if that matters to you. I know I support quite a few things now that i used to enjoy about 5-10 years ago but didn't have any money back then. If you don't care about Android users at all then I have nothing against you either. I see people shouting for Android port in comments a lot. Most are solely pirates. You are not hurting your bottom line by ignoring them in any way as the OP may have pointed out. Just having the highest number does not mean they are all paying.