Gimp for photo manipulation and Krita for digital painting.
GIMP is free and very good. GIMP can be a bit cumbersome, but it's free. You're simply not going to get the equivalent of something priced like photoshop for free. But, once you get the hang of it, it's quite functional and while I'm a novice, I'm quite proud of some of the stuff I've been able to output.
Krita have Lots of YouTube tutorials. Super easy to learn. I can't recommend it enough.
I have a XP-Pen Deco Pro ( https://www.xp-pen.com/product/432.html ) drawing tablet which is fully supported by Krita and GIMP , it works well ,speed my work .