Google Search is way worse than it used to but still beats DDG by a mile.
I've tried SearX and it was meh, maybe there's some better instance than the one I tried though.
Yandex is good for reverse image search and when the American government makes western search engines block certain search results, but not that useful in general. Also for a period Yandex just kept bombarding me with endless captchas and was completely unusuable
Bing search is just DDG, or well DDG is just Bing.
Baidu search, tbh haven't tried it much, but even for chinese I had better search results on google search so yeah
Just the other day I was looking into how to use a single shared WINE prefix for multiple users since it's not like any 2 users would ever use the same PC at the same time... TIL I was wrong
Unfortunately I don't really have anything helpful to add except it seems like Linux is more or less inherently built to support what you're looking for.