Not the OP, but I use my Macbook Pro M4 with a 5-year old Dell TB19 Thunderbolt dock (not the usb-c one!). I have 2x 1080p screens aged 10+years connected to the dock, and I use the Macbook as 3rd display and the keyboard of the laptop as my daily driver. I've used the very same setup with my 2019 MBP so I assume the M4 Air can handle it too.

I have had really good experience with OWC docking stations - rock solid compared to Dell ones I've had in the past: https://www.owc.com/solutions/connectivity

I won't recommend my monitor because it has auto-dimming you can not turn off. Good but not great.