I'm still on Mojave (10.14!) and it's just brilliant compared to the more modern MacOS. There's a Firefox fork called Momiji (https://github.com/aobaharuki2005/momiji-web-browser) which backports recent Firefox to very much older macOSes, and basically I still use 32 bit x86 applications sometimes.

My next laptop computer (which is sorely overdue) will be Linux with macOS in a VM.

A pity, because Keynote is great.