thepianoplayer416 Many programs including Acrobat, web browsers, Adobe PhotoShop, MS Word, etc. can open a PDF like a picture file. There are programs that can convert the text in a PDF back to something that can be edited in MS Word. Converting a PDF to a MuseScore file can be tricky since the resolution of the content in a PDF file can vary. In most cases you're not going to get everything converted correctly so some editing afterwards is required.
I can't say anything about MuseScore since I transitioned to Dorico from Finale, and have gone much further already with Dorico than I ever had with Finale. There I've only read about importing via HML - haven't tried to go PDF => Dorico.
But I do know about PDF => MS Word. I use this all the time, and it is not at all perfect. I work as a translator. Most material clients send me is in the form of PDF scans. I can convert these to MS Word and thus get a word count. When there are numbers, and especially codes like "743ABC1234567 224XY!Z" it is easier to copy and paste, and more accurate than writing it out. However (1) There will be errors. (2) Formatting can be wonky.
In terms of errors, 8 often becomes B; zero can be the letter O, or the letter O can be rendered as a zero. A diacritic such as a French accent can show as what it is (select language before converting) or become something weird. It is far from perfect.
I always create my own file with my own formatting, and copy and paste things like numbers and proper names over. If I try to write "on top of" the converted file, I can find some hidden formatting creating a mess. If the target language uses more words, suddenly you can't fit them into that space, and you'd need an IT degree to figure out what got formatted and how to undo it. Converting TO PDF is easy: converting FROM PDF has major hiccups.
I can imagine, therefore, that conversion of PDF notation into MuseScore and other music programs might be at least as iffy. Converting from: easy peasy.