Has been for a while, assuming you can get work done on the iPad UI. It doesn't do a normal mouse and there are some limitations to things like screen dimensions.

Works in a pinch but Apple is not going to compete with themselves on this front, they're expecting you to buy a macbook for serious work and an iPad for work in a pinch.

Had no problems connecting iPad Air 4 to external display via USB-C DP. Have not check whether periphery devices work this way though - I used BLE keyboard.

yes. Has been possible since at least M1.

Buy M-based iPad, nice monitor, keyboard and mouse. Connect mouse and keyboard to monitor via USB. Then iPad via USB-C/Thunderbolt to monitor. Everything "just works" and you can handle surprisingly high amount of work this way

I was about to ask the same. I'd like to get an ipad for the same purpose. The iPad pro can for sure, but I don't want to spend ipad pro money.