> But it only lets some of the system shrink; for something like a mains charger, you still need the isolation magnetics, so your overall size is still constrained.

1. You can isolate with caps... if you trust their manufacturer. http://www.helixsemiconductors.com/uploads/cms_uploads/2018/...

2. Well if things go this way, one can go for "virtual isolation" with beefy mosfets, and pray that the gate fail before the junction melts to pieces. This is actually what apple recently patented.

Nice to meet an actual engineer here. What is your field of work?