But there’s no way she’d have just “known” this, and it’s just another hurdle to non technical users. Why should you have to know that Ubuntu is a downstream distro of Debian to install a program?
It's also something that is answered effectively with the very first Google result for an obvious search: https://www.google.com/search?q=should+i+install+deb+or+rpm&...
There are a few ways round this but they would generally require action on the part of all the software suppliers who post packages via websites. In your example it wouldn't be hard for MS to figure out the Ubuntu users and send them just the right link and likewise several other Linux distros - I guess it's still not worth it.
Maybe this is an area where a JS library for websites would avoid each one rolling their own and thus make the experience better across the board?
Just say "teams doesn't work well on my computer, it's very poorly made. Can we use jitsimeet? It's much easier for me." and them drop them a jitsi link without waiting for their response.
Teams is the official video chat at my company, I've been successfully ignoring that for more than 2 months now. At this stage, jitsi usage is starting to spread to other teams.
For my parents it's simpler to go with OSX.
For working on print, Inkscape and Gimp pale in comparision with adobe's suite. Not to mention sharing files with the "de facto market standards" world .
For working on audiovisuals, no cigar.
For working on development, well, none of my external hardware was supported (my last experience was Ubuntu 18+) but ok, the IDE worked.
In any case, going to the original question: normal user who?
Gimp: Agree, most features are there but finding them is a chore
File sharing: Illustrator uses .ai files which are .pdf (compatible with inkscape), can't speak about .psd compatibility with Gimp, never tried it
Audiovisual: DaVinci Resolve is awesome, and adequate for most if not all home users
Development: I'm assuming you mean embedded development, this relies on support from the vendor, community can't do much about this. Most development are not embedded developers, and in my experience boards by SiLabs worked pretty much out of the box. Obviously anything web (except ASP I guess, I may be wrong) is a breeze on Linux
Regardless, the normal user needs none of this. They need a web browser and an office suite. The Linux ecosystem needs a more intuitive office suite, but libreoffice is good enough and Google Docs/Office365 online work for many people too