I recommend dbi (https://github.com/rashevskyv/dbi/releases/tag/336) (you only need the nro app)
You don't need anything other than the app itself on your switch and here is explained how to install from usb https://github.com/rashevskyv/dbi/blob/main/README_ENG.md#run-mtp-responder
I think the most important thing you need to remember is that when you update firmware you always have to install latest sigpatches. If you forget that your games might not boot at all
btw @BigOnYa the health bar doesnt decrease when i take damage (and yes i put the "at the beggining of the scene change value of greenflatbar: set to Protagonistcopmode.Health::Health())
@Xdqwerty there is health behaviour you can add to your character, then to use a health bar is lil more complicated, google n watch a few tutorial video on it, be too hard to explain here.
I know you have to create a health and health max variable. Then there is a calculation you use in code to subtract width size of the health bar. Google few vids.