I went with these baffles front and back.
NVX XBAF65 Foldable Silicone 6.5" Speaker Baffle with Egg Crate Foam, one Pair/Box https://a.co/d/5xKRqMw
I used the Kicker KS Series so far in all 3 locations (6x9 in front door, 6.5 in rear door, and 2.75 in dash). The dash speakers came with the plates to mount them.
I also went with these rear door adapters. They are a lot sturdier than the ones Crutchfield sent. They also move the speaker out closer to the door panel.
RED WOLF Front/Rear Door 6.5" Inch Aftermarket Speaker Update Install Speaker Adapter Bracket Spacers for Chevrolet 2006-2021, GMC 2006-2020, Some Cadillac, Buick, Pontiac https://a.co/d/7pDReV6
I do have a pair of PowerBass 6x9's coming to try in the front doors. They are a dual voice coil that can be wired to require 2 ohms from the amp. Since the front door speakers were 2 ohm, I'm hoping these help with the sound. The Kicker 6x9's sound better than the OEM speakers, but still not what I'm expecting. I know my expectations shouldn't be high without adding an amp, but our 2020 Equinox factory Bose system rocks (granted the Equinox is a 7 speaker system). If I can get the truck close I'll be happy.