I installed Winamp full version in its default Programs location rather than an external hard drive, and it worked. I really wish I could've kept it portable, but whatever.
In regards to pxtone, it wasn't easy getting it. I spent days googling trying to find a .dll that would actually work in xmp only to finally get a message saying it's flat out incompatible (the output changes and xmp doesn't like that). It does work in Winamp though. Go here and get in_pxtone.dll
Readme in Japanese takes you to a dead link (which is an outdated link to Pixel's official site). So you download pxtone v0.9.1.4 (must be this version, the dll isn't in future versions) here:
Then take pxtone.dll out of that and put in-pxtone.dll and pxtone.dll in WinAmp\Plugins and it works. Kind of. I tried about 10 different tracks, and all of them played except for one released in 2015. That one would only play in the most recent version of pxtone as well. I'm not sure if they can't play any tracks made in the newest version or just ones that use newer features because another one from 2015 did play in WinAmp.
Pxtone contains sample tracks that you can use to test, or you can download some here: