I think alt-tabbing or virtual desktops has less mental overhead and physical strain than using VR though.

This is a good point. I thought about it, too.

I could see a frequent traveler using an AVP as a "full setup" on the go. In my experience, I can get away with most with a MacBook. Some projects really benefit from the extra screen real estate (and a mechanical keyboard.)

For me, the problem is that if I don't see it, it doesn't exist. Slack, server monitoring, other communications channels, they all take up real estate. My daily driver is a 43" 4K monitor. Basically 4x 24" 1080p monitors in one. It's the exact opposite of portable.

I can get any task done with my laptop. But not a full day's work. And if I want to travel while I work (which I would like to do) then I need a better solution. This is why I'm looking into VR and also a 4K projector, but a projector would have to be able to be seen in a bright environment, and I don't know what the current state of projectors is.

Look up laser projectors. Random article: https://www.hisense-usa.com/post/laser-light-projectors-vs-l...

Looks like 3k lumens is your maximum. https://www.google.com/search?q=3000+lumen+projector+in+dayl...

Its less mental strain to just lay out the windows spatially. Who doesn't like more monitor space? However, its much more physical strain than multiple monitors.