Imgur if you want memes, cats, and politics, but keep in mind that they’re not much better than reddit. No 3rd party apps, and the official app has ads & sells your data to Facebook. You can block it by using the DDG app and enabling App Tracking Protection, however. Also setting your phone’s DNS server to dns.adguard-dns.com. You should be doing those two things anyway, regardless of what apps you do or don’t use.
Like the others have said, use Voyager to filter out the instances and communities you don’t want to see.