I have a small business as an independent LSAT Tutor (for U.S. and Canadian law school admissions) (95 percent online, with occasional in-person students). For a couple years, I was iPad-only, with an Air 2 and a 2017 12.9. As I write on an online whiteboard a lot, and I also travel a lot, this was a huge improvement over traveling with MBP plus Wacom tablet plus iPad Air 2 plus books, as I used to.
I've been traveling less, both because of COVID and because I'm no longer dating someone in Europe, and about a year or so ago, I decided I wanted a Mac mini with a nice big monitor, so I could put my various reference materials, etc. all up next to each other on the screen. I use my 2018 11 inch in side car for even more screen space, and I use my 2018 12.9 for drawing on the whiteboard.
And then when I do travel, it is my previous practice of using my 12.9 as my main interface for Zoom, drawing on the whiteboard, etc. and my 11 inch for reference materials.