Ironically, one of the reasons I went with Android instead of iPhone last time I bought a phone was that I could use my MacBook charger with it.
Sure, you have 1 more cable to throw in your bag but it's not a big deal.
So you would need compatible cables to make fast charging work, and then it will only fast charge up to 80% and then slow down.
USB-PD is the standard for power delivery and Apple (and Google) both rely on that, so if it's USB-PD compatible it'll support the quickest charging it can handle.
That should be fine. There's a protocol for the charger and the device to communicate and decide what power to charge at.
Unless explicitly negotiated by both ends, every USB-C charger outputs the same boring 5 volts as classic USB, so the headphones should charge just fine.
The switch dock demands 39 watts, which implies 15 volts, but the switch itself will negotiate any voltage when standalone.
In fact, I am doing it right now.
Output on the adapter reads: 5v@1.5A/15v@2.6A
The only time things break is when you attach a broken charger that outputs 9 volts onto a wire that's supposed to be doing 2 volt signals.
Also some devices don't support anything else but USB-A to C cable that comes in a box. That's why I returned JBL Charge 4 and got Anker Soundcore Motion+. Much crispier stereo sound at expense of some base.
Unfortunately a lot of devices are out of spec like the Nintendo switch which can be damaged by an in spec charger.