Phew... Finally finished it. Kinda.
You'll find the mod itself plus control customization program here:
https://disk.yandex.ru/d/srDrlvR3OEtKTA Installation:
1. Run the game and enable wormkit modules support in settings, obviously.
2. Download the archive
3. Unpack it to any location of your choice.
4. Run wk-gamepad-config.exe
The mod will be installed and you'll see the control customization program window. It may be a little complicated, but I have left a lot of explanations thoughout the program; just hover the row in a table that you're confused with and you'll see a popup with explanation. Also there are blue question marks with tooltips too.
Both DirectInput and Xinput are supported, however, Xinput is more recommended (if your gamepad supports it) as it has more clear button/axes names.
For Wine users: run the program's exe within the Wine prefix you use to run the game.
Large credits to
@nizikawa as he taught me everything from scratch. Now he can be kinda proud of his student