I have a Samsung A11 I got from RW 6 months ago. Presumably it’s “unlocked”. Can I try [for example] Consumer Cellular for a few months and come back if it doesn’t work for me? Both RW and CC have “Bring your own phone” so will RW let me use that to come back with the A11 I bought from them?
Yes, that’s no issue. You may need a new SIM card depending on the type you have. If when you open the Republic App, tap the little gear at the top, and then About you see “GSM” under SIM Type, you would need a new SIM if it is more than 20 days after leaving. If on the other hand you see “CDMA” hold on to that SIM, because you can reuse it.