Right now it is possible for people that don't own pico-8 to play games through the web system. Will it ever be possible to send people standalone pico-8 games that run on windows / mac without them purchasing a copy of pico-8?

I've just started playing with pico-8 (it's really cool, really enjoying it) and came here to ask the same question :D

Is there a way to capture the HTML5 output and embed it in a stripped down browser app thingie à la construct2? That'd do in a pinch. Is it even allowed? (I don't see anything in the licence covering that).

During alpha (and quite soon in fact), I'll make an HTML5 player available that is licensed to be distributed bundled with cartridges you've made. This will also make it possible to post games to Newgrounds and itch.io etc. I'll look at the possibility of doing native binaries in the future, but I'm not keen to commit to that at this stage!

This is good news :)

Thanks for letting us know. Time to look at html5 app bundling software again then :)