I don’t remember if I’ve shared this before but I was reminded by seeing that Clip Studio Paint can work on Linux via Wine. (Though apparently there can be difficulties and CSP can be expensive to buy outright or involve a subscription?)
If you happen to have an iPhone (even secondhand and as old as iPhone 13… which is still pretty new tbh…) you can buy Procreate Pocket for a one off of $9.99 to draw on your phone with your finger or whatever cheap stylus. Procreate for iPad is $19.99.
For Android there are free or cheap options (Reddit link).
Ibis Paint seems to be a popular option (Reddit link) for Android phone (free with in app purchases) but isn’t the only one. Apologies that I can’t find a neat list of free Android apps that are specifically for phone - even with Boolean search the search engines seem to have enshittified and I am tired.
Ps. Some might say that having an iPhone or iPad isn’t frugal.
However it might have been a gift, bought before hard times came, secondhand, a work phone, part of a family plan, a loaner, a donation from a domestic violence service, or simply bought for the functionality to do everything without buying a separate computer.
Let’s not fuss about it. I think we can all work to get the most out of what we have regardless of what it is.
Not sure if it's what you're looking for but I use https://photopea.com a lot, I didn't need Photoshop enough to pay for it and this is a very good alternative. It's a website but everything happens on your local machine.
On my iPad I also use Respite for pixel art since Aseprite doesn't have an iPad version.
That looks great