Practice with Pronouns is a site that lets you practise subject, object, possessive, and reflexive forms of English third person pronouns. It comes with a few of the most common options, but you can also fill in whatever pronouns you like. Useful for both English learners and people wanting to practise using nonbinary pronouns.
As if it couldn’t get any more delightful, it often uses quotes from Welcome to Night Vale in the practice sentences, which is definitely far more entertaining than See Spot Run. The feedback sentences are also very cute.
(Hm, I’m pretty sure the second blank in that screenshot should have said “xyr”, in retrospect.)