On Chromium touch screen emulation feels much better.

I find them both pretty poor compared to running on emulators/simulators

One of the reasons I stopped using Firefox was that the columns in the devtools were unexpandable. I couldn’t see any data past what Firefox decided was enough to show. Did they fix this?

I'm assuming you're talking about table views like the Network or Storage/Cookies tabs? You can resize columns and each cell has a tooltip that shows the full content if it's hidden.

What cripples FF DevTools for me is being unable to find the setting for timeout on HTTP GET, during full-stack development. If I've set a breakpoint in a debugger on my server and proceed to single-step there, FF aborts the GET request with an error. So client-side JS doesn't see the eventual result of the GET, it has to recover from the error to proceed, e.g. by a full page-reload.

Chromium, last I tried it, by default sets the necessary HTTP timeout(s) to infinity if its DevTools is open.

My searches of Firefox docs/wiki, StackExchange, HN Algolia for a fix have come up empty.

Navigating to "about:config" and searching for "timeout" finds 27 different settings prefixed with the substring "network". Some are obviously in units of milliseconds, others perhaps whole seconds.

Anyone know which one (or what combination) might incant the necessary black magic?

I really like that the Chrome profiler shows you the profile right there. Firefox insists on opening the profile in a browser tab. This is fine, but is an unnecessary context switch for me.