there's some cool stuff in the works but it doesnt sound like there's a plan to internalize the work into devtools but to keep it as a web app and rely on a serviceworker for "localness" - not great, imo.
My impression as a web user is that if any devs actually use the performance inspector it's just to learn their site is slow and then not do anything about it.
Your devs might develop perfectly well behaving stuff just to see it get totally obliterated by loading 3 external tracking scripts through Tag Manager, three different pixels and 7 external contact form/chat bots/newsletter popover scripts from their CRM/ad platform/whatever crap marketing wants.
Sadly noone cares what the performance inspector says. Newspapers just get slower and slower. Our local newspaper takes 15 seconds to first visible paint and another 5-10 seconds to usefulness on my phone...