[Ataraxic]

The question is that it seems to emulate many things, but what doesn't it emulate well?

It looks like it's built off chromium, so I'm assuming it wouldn't be able to show an issue that only appears in safari or maybe Mozilla?

Perhaps this is in the docs.

edit: It's in the FAQ at the bottom. Still, beyond the actual browser engine, are there other known limitations?

[kilian]

This feels like a lay-up, but here you go :) https://polypane.app/docs/emulation/#emulation-or-simulation

Polypane doesn't simulate the specific rendering engine of other browsers, it just pretends to be another browser (which is what emulation is) so you can test that the code you wrote for those browsers (for example, a polyfill) responds well. You'll still need to test in those real browsers to check against their rendering bugs or support gaps. (but something like Polypane portal[1] can make that step much easier)

[1] https://polypane.app/docs/portal/

[jbreckmckye]

Perhaps there's a way you could remotely render a page in Firefox, Safari, etc? And then stream into the viewport.