There are ways to grow your instagram followers
First is by hiring a specialist that will grow it organically for you.
Second is by buying fake Instagram followers which I personally will not advice.
Third is by building it organically yourself by posting regularly; reels, stories and also following some account does help in boosting your followers.
As an expert I would advice you to hire a specialist. It is the safest, stress free and fastest way to grow your account. If you decide to hire one I have the right specialist for you just give me a call.

You could sell your artworks as nft or print on demand. I don't know much about nft but for print on demand you could use sites like dazzle.com, redbubbles. You can search the net for more because there are many more sites out there

Also your work is very nice. It's a 10/10 and what you need most is to grow your IG followers. By doing so you have a higher chance of getting buyers to purchase your work without you even starting a print on demand business.