Resources
Here are some resources I've used, and recommend, if you're looking for song files.
Guitar Pro, .gp* Files
I've been thinking of unstrung for a few years. I finally found the motivation after hearing friends rave about AI coding. Then I got really motivated while going through some lessons on Totally Guitars. It's a site much better at creating guitar lessons than building accessible, usable websites. It's also a good place to find .gp* files for hundreds (thousands?) of songs.
I have purchased several lesson packs and generally enjoy Neil's teaching. Unfortunately, the videos often assume you are following along with the tab sheet (generally a .gp* file). Now, with unstrung, I can read the tab sheet and follow along with the videos.
Another good site for .gp* files is Songsterr. Unfortunately, you need a paid subscription to download the .gp files. It's not a long term commitment though, and I have not come across a limit on how many files can be downloaded a month. Their files are crowdsourced and tend to be more complete than those on Totally Guitars. They tend to be more complicated too, though. Totally Guitars might be a better place when getting started. Songsterr might be better when you really want to get into the eighth and sixteenth notes.
Songsterr is also not a very accessible or usable site. With patience though, I was able to create an account and figure out how to search, find the search results, and find the download. Search is exposed as an editable text field. Type in your search and press enter. Wait a few seconds (there is no audible indication anything is happening), then in browse mode move to the next link (k in NVDA). If it found anything, the results should be in the links after the search box.
Once you've clicked on a search result, you go to the page for that song. It seems to put me directly on a "play" button to hear a MIDI version. On that page, search for "download". It's in a set of tabs, I think near the end of the page. Press enter on the download tab to select it. Immediately after selecting the download tab, I press ctrl+downArrow and hear "dialog download tab." Press enter on that and you get, I guess, a popup dialog with buttons for which format you want. Choose the Guitar Pro button and you should get a standard dialog for where to save the file.
MusicXML
I could not find good resources for MusicXML files. I tried to poke around MuseScore, which is supposedly a good resource. I could not make sense of that stinking pile of, probably React-based, HTML. If you know of good MusicXML sources, email feedback@eyesunstrung.vip.