The last result as a painting photo/image could be free, painting itself should be paid. But the making process, describing the emotions & motivation while working, painting tips & tricks, etc could be subcription based (like youtube join, or as you said patreon like thing)
Discussion
Yes of course, but how many people do you think, in Nostr's current state, are willing to do this for an unknown, emerging artist like me?
Yes it is unknown but we can't find about without trying. Plan your process and I'll support as much as I can, and I believe people who admire your work will follow...