You can test for citizenship at the 3 year green card mark. I married my wife while she was on a tourist visa during covid. Having been married less than 2 years on the day of our appointment, she has only a 2 year conditional green card and we have to reapply to have conditions lifted within the last 90 days of the 2 years. However, if that appointment then doesn't actually happen until the 3 year date of the conditional green card issued, as it apparently happens for some, we can also apply for citizenship at the same time at the same interview. I think we will have to add the citizenship paperwork, but the official will first interview us both to lift the condition on the green card, and then i will leave the meeting and she stays for the citizenship interview/test. That was described to me by our immigration official who interviewed us for her conditional green card.