I received the Astropad Luna Display USB-C dongle. It works as advertised. A bit expensive at $90 but worth it to me.
Original set up was not too hard for a tech challenged person like me, took under 10 minutes including downloads and I got it right the first time. You could do it even faster.
You do need a separate monitor only for the first time set up, but not after that.
I have mine connected peer to peer wirelessly. I tried wired with a Thunderbolt 4 cable and it makes a minimal difference as the wireless is rather good. Need to experiment with this further. And the iPad magic keyboard does work, as does the touchpad and and the touchscreen on the iPad.
My only nit to pick is you do need a separate keyboard to enter your Mac’s password as the iPad magic keyboard is still not connected. No problem as I have a regular and a palm sized bluetooth keyboard and my password is easy enough to do without seeing it. After the password is entered, it takes maybe 15-30 seconds to fully connect. Perhaps there is a setting in the Mac to connect even on the lock/startup screen? Maybe the wired connection?
Switching between the Mac and iPad on my iPad is just a mouse click.
Would I buy it again? Yes!
I would recommend the larger iPad for the extra real estate, but still running my MacMini on my 10” iPad is great!
Photos are compressed to fit so quality is degraded a bit. I do get my full iPad screen resolution.

