it's a meta-search engine (a search engine that searches through other engines). I self-host one myself (although I host SearxNG, a fork). You could argue you can be identified because of the same IP, so you shouldn't self-host for yourself only - but there's very real legal and practical limits to tracking without cookies, so I'm reasonably fine with this, especially since I'm not the only one using my instance (although the user count is under 10).