Yes it would work pci-e backwards compatbility for nvme works better than GPU backwards compatbility but it will only run at pci-e 2.0 however I think that windows runs better on nvme than sata ssd. My system feels more stable and responsive though they say you can't tell the difference I'm happy with running mine at pci-e 2.0 and I can just flip the drive to a new mobo when I upgrade.
The power requirements of a stronger GPU might not get on well with a pci-e 2.0 port so you'd have to go for something with a conservative power draw modern gpus could cook the pci-e slot and fry your mobo.
An RX 6600 is 132w so 75w from the socket and the rest from a pci-e connector from a power supply is under 150w so is a gtx 1660 super 125w power draw however both are lo-end ray tracing cards probably ok for 1080p but starting to struggle at 1440p
6600 vs 1660 super - gpu monkey.
rtx 3000 series pssh probably will blat your mobo even a 1070 or 1080 might be too much for it. There was a phase when GPU power requirements went up around 2015
and there were power issues with some cards on pci-e 2.0 mobos and on the amd side too.
You don't really want to be experimenting and break your board since it couldn't be reconditioned or replaced and if you are still able to run some games you like at 1080p it's saving you some money for the time being. Tiding you over 'til your next upgrade so don't push your luck too hard.