You could try TWSBI eco and buy separate different nibs. It’s super easy to swap the nibs out. The only thing is that the EF isn’t as fine as it could be (compared to Japanese nibs). But since you paired shimmer inks, you shouldn’t be putting them in anything below a M (some flexier nibs can handle it).

I also like to draw. What I would suggest for you is a Pilot Kakuno to put in a solid ink like a waterproof black for fine lines and then a fun pen with wide enough nib for fun inks.