There is plenty of debate going on about this - QB play has been down this year and there will be many QB hungry team this offseason - I could see the Panthers, Steelers, Giants, maybe even the Saints enquiring. I think we will see the top of the market move first - Rodgers, Wilson, Watson are the main guys, who could be traded depending on their circumstances - and then Kirk will come next. I think they could get a high 2nd / late 1st, and the team acquiring him would have an extension in place.
The void years are a tricky subject, but it's basically allocating a signing bonus over fake years. They basically moved $9M from 2021 to 2022, and I believe the only way to alleviate it is to extend Barr, which would then make $4.94M hit 2022 and $4.94M hit 2023 on top of whatever the extension is paying him.