As for Tess' affection/emotionally attached for the characters and Alessandra in particular..Well, she's written for a very long time that Alessa is a special and relatable character to her, so there's nothing surprising about that. So, yes - both the Secret Sub route itself (the only true femdom in this game, according to Tess) and Alessa herself as a character, mean quite a lot to her and are kind of a favorite...
Yeah, the idea of a deeper Dom romance with Alessa (without Celeste) definitely makes sense. And I'd really like that too...I started this relationship with Alessa and Celeste purely for the sake of that beauty with the bottomless green eyes. And the idea of turning Alessa to the light without Angelica's help seems pretty logical too. If SS Kane can do it, then it's logical to assume that pure Dom Kane can do it too.
Ofc, that doesn't mean I'm going to give up on hypothetical and super-hot joint scenes where pure Dom Kane, along with Angelica with a strapon on her hips, re-educate Alessa by "turning her to the light", haha.
As for Astrid, I've always liked her, but when I wasn't banned on Tess discord yet, I just remembered that she said something like Astrid would never be available as a LI. Well, if I missed something and the situation has changed, I'll be glad.
At the very least, a possible deep romance with Astrid on the Dom route could have been a real gem and added motivation for the players to "abandon the game show route" in favor of Island 4 and all that comes with it. Either way, Astrid as a full-fledged LI for "white knight" Kane sounds great and right.