Good read, and I think you might want to look at OnlyOffice. It's open source and while it is kindof a shameless Microsoft Office clone, it does seem to support LaTeX when adding equations. Not sure how well it works as I don't use it though. The slides app is pretty decent, the only bone I have to pick with it is that there aren't many animation types and most of them are very basic. Otherwise, might be what you're looking for.
Edit: I just tried it and it seems to work pretty well. Select LaTeX, type your equation, then select professional in the dropdown menu and it'll show the equation.
That just because I'm a programmer that must mean I'm a master of anything technology related and can totally help out with their niche problems.
"Hey computer guy, how do I search for new channels on my receiver?"
"Hey computer guy, my excel spreadsheet is acting weird"
"My mobile data isn't working. Fix this."
My friend was a programmer and served in the army, people ordered him to go fix a sattelite. He said he has no idea how but they made him try anyways. It didn't work and everyone was disappointed.