Verification trouble

If I had been talking with people in messages on Facebook and my account had an ID verification checkpoint that I won't complete, can I somehow download and sign into Messenger with the same account credential and talk to those same people or not? I'd try it myself but I'd prefer not to have Facebook's spyware anywhere near my computer.

As far as I know, that's not possible.
If tjhey block you on facebook and request photo ID or something like that, messenger will be blocked too.

Yes, you wont be able to use the account anymore on messenger, You need to pass the verification first