Welteam The basic dongles without any advanced features are generally fine, the problem is the Google delivered ones are poised as a Fire Stick competitor, so they have a lot of needless junk if all you need is screencasting... I wish Miracast wasn't a security nightmare so the industry didn't abandon it.
Here is a nice article about DisplayLink, as well as some compatible adapters: https://dancharblog.wordpress.com/2020/09/16/run-4-monitors-from-a-laptop/
It's a bit older and poised for laptops but the content about DisplayLink is still relevant to the Pixel 6 line. You may be better off getting a cheap dock and using a USB DL adapter from the dock's USB hub, as long as the dock supports running the hub ports in host mode it should work, but YMMV.