On Linux KVM is what people use for this. Not an option in VirtualBox.

Yeah, Jerboa has been a buggy mess the entire time I've used it and this finally got me to try Voyager. 10,000x better experience. I know developing an app is not easy and I hope Jerboa can get through its growing pains, but Voyager is great right now.

It would be nice if they fixed their app so that when I set it to always dark mode, it actually stays in always dark mode. I don't have much faith in UI improvements when that bug has plagued me for literally years, across Android versions and devices. But now the colors that suddenly blind me when it changes from dark to light will be different, yay?

That is insane. Straight up blacklisting popular software because they don't want people to look too closely at what they purchased. It's amazing what the public is willing to accept, just such a constant stream of reports about bad behavior from companies that most people can't find the energy to care.

Either go with working through textbooks on your own, as has been stated by others, but that approach requires tons of discipline as the subject matter can get quite dry and frustrating at times. Or, I'd say ideally, enroll in courses at a local community college. The one I went to had four calculus classes, linear algebra and differential equations, along with statistics and I believe some kind of math programming course (my have just been part of other classes). So you cab get into fairly advanced stuff going that route.

If you want to learn even more after that, you'll have a solid basis to continue self study. Hell, you might even have a good start towards a bachelor's in math.