A 3D model which you can rotate and practice drawing from any angle. (Some models are parametrized and their proportions can be randomized.)
Instagram seems to have died, too.
All platforms eventually die, superseded by the next cool new thing. Don’t invest too much in one platform, and create for the long term.
Create things that will be valuable ten years from now. (A post on Social Media is not that.)
I make my weekly articles timeless, and I hope they are as valid as they are now ten years from now.
Create things you enjoy, and other people will like your work too. You can do anything in your sketchbook without worrying about how an audience will respond. If you like it, there will be an audience for it; others will also love it.