Subject and object propnouns:
https://elt.oup.com/student/project/level2/unit2/grammar/exercise4?cc=global&selLanguage=en
https://test-english.com/grammar-points/a1/object-pronouns/ (3 exercises)
https://www.perfect-english-grammar.com/subject-object-pronouns-exercise-1.html
https://agendaweb.org/exercises/grammar/pronouns/object-1.htm
https://agendaweb.org/exercises/grammar/pronouns/object-3.htm
https://agendaweb.org/exercises/grammar/pronouns/object-4.htm
https://agendaweb.org/exercises/grammar/pronouns/subject-object-1.htm
More practice, but with possesive pronouns and adjectives:
https://test-english.com/grammar-points/a2/subject-pronouns-object-pronouns-possessive-pronouns-possessive-adjectives/3/ (3 exercises)
https://agendaweb.org/exercises/grammar/pronouns/subject-object-possessive.htm
https://learnenglishteens.britishcouncil.org/grammar/a1-a2-grammar/personal-pronouns-possessives (explanation and exercises after)
https://www.englishexercises.org/makeagame/viewgame.asp?id=2842
