Your mileage may vary, but I've been collecting cool in-between tools for a while that do things the big programs are either too big to do, or substitutions for tools that become too expensive.

Photopea - A web application that can open Clip Studio Paint files without needing the app installed. (I use it on my aging laptop because I'm worried that if I burn a license key, I'll have to re-purchase Clip, which will suck)

Piskel - I love Piskel because its interface is just about as simple as MS Paint and it does what it needs to do simply, for free, and better than other programs with less approachable interfaces.

Clip Studio Brushes

1. https://assets.clip-studio.com/en-us/detail?id=1750080 - Nice watery graffiti look that works well with how I press the stylus to the screen
2. https://assets.clip-studio.com/en-us/detail?id=1784777 - Buttery smooth brush that's great for blending or smooth color gradients