The legless avatars seem to be mostly a VR thing.

It would be cool if you could mix the two. What if you could meet a group of friends at a coffee shop but if one of your friends was out of town you could have them join you virtually?

The avatar may or may not have legs. We could leave that choice up to the individual. Maybe they want legs. Maybe they want to be a little floaty ghost. Maybe they want to present as a talking frog.

The big tech companies keep trying to sell AR as a gateway to their private alternate realities. That misses the whole point of AR. It's supposed to augment reality, not replace it.

Everyone who has played video games knows what AR is supposed to look like. Create an API to let developers build widgets and allow users to rearrange them on a HUD.

Obvious apps that would get a ton of downloads:
floatynames - floats people's names over their heads
targettingreticle - puts a customizable icon in the center of your screen so you know it's centered
graffiti - virtual tagging and you control who sees it
breadcrumbs - replaces the UI of your map software to just show you a trail to your destination
catears - add an image overlay that makes it look like your friends have cat ears healthbars - they're a really familiar visual element that you can tie to any metric (which may or may not be health related)

I imagine being able to meet my friends at a cafe that I've never been to. It's easy to find because I just follow a trail of dots down the street. As I get closer I can see a giant icon of a coffee cup so I know I'm on the right block. Not everyone is there yet but I can see that the last of our friends is on the bus 2 blocks away. I only met one of them once a few months ago I can see their name and pronouns. We sit around discussing latte art. I get up for an other cup and see from their health bar that one of my friends is out of coffee so I get them a refill. On the way out I scrawl a positive review and leave it floating on the sidewalk.

Is it practically feasible to regulate the training? Is it even necessary? Perhaps it would be better to regulate the output instead.

It will be hard to know that any particular GET request is ultimately used to train an AI or to train a human. It's currently easy to see if a particular output is plagiarized. https://plagiarismdetector.net/ It's also much easier to enforce. We don't need to care if or how any particular model plagiarized work. We can just check if plagiarized work was produced.

That could be implemented directly in the software, so it didn't even output plagiarized material. The legal framework around it is also clear and fairly established. Instead of creating regulations around training we can use the existing regulations around the human who tries to disseminate copyrighted work.

That's also consistent with how we enforce copyright in humans. There's no law against looking at other people's work and memorizing entire sections. It's also generally legal to reproduce other people's work (eg for backups). It only potentially becomes illegal if someone distributes it and it's only plagiarism if they claim it as their own.