The dev branch does, or at least seems to mostly do:
Step 1. Get the base 0.51.1 game:
https://f95zone.to/threads/lab-rats-2-v0-51-1-vren.7260/
Step 1.5 >.<: Get the Ren'Py update:
https://f95zone.to/threads/lab-rats-2-mods.32881/ (thank you, Eldoen!)
Step 2. Get the dev bugfix:
You must be registered to see the links
(click on the green CODE button, "Download ZIP")
Step 3. Unpack the bugfix into the MAIN folder (do manual extraction - move "game" folder from the package, otherwise you'll get a mess), so that it merges with your base "game" folder, override all files
Step 4. Get the dev mod:
You must be registered to see the links
(click on the download icon left of the blue CLONE button, "Download source code" as zip.
Step 5. Unpack the mod into the "game" folder - NOT the main folder! Again, do manual extraction to get the "Mods" folder where it should go (into the "game" folder)
Step 6. PROFIT!
Sounds more complicated than it is, but just for the sake of clarity:
The installation structure looks like this
-Main game folder - Unless you renamed, likely "Lab_Rats_2-v0.51.1-pc"
-- within the above, a "game" folder and other stuff
---within the "game" folder "Mods" sub-folder and other stuff
For some reason, I can't get the daily serum to work right now, though. Policy purchased and active, each character has both daily and weekend dosage assigned as work duties, the serum is chosen for all divisions, but it just doesn't seem to trigger. Have 50 doses in stock as well, so at this point no idea what's going on. Second fresh installation this is happening on, so possibly something with the work duty assignment code messing things up would be my guess.
Also, the cheat menu does not update all values on its GUI, but seems stable and playable as far as I got.
You can always override your installation with newer commits, usually it doesn't cause issues as long as the base version matches. Make sure to check both the bugfix and mod branches somewhat regularly for updates. I generally just download both again and override (bugfix first, then mod) whenever I get back to playing.