I suspect the usb-PD standard doesn't allow for raising the voltage any more than they already do

Even if usb PD could go up to over 9000 volts, it can only provide fixed set of voltages, none of which can really match what every tip requires

Actually that's not true anymore, PD Revision 3.1 has an adjustable voltage supply mode that can do any intermediate voltage between 15-48v, with a maximum power of 240W: https://www.usb.org/usb-charger-pd

I don't know how widespread support for that is though.

PD2.0 is here for a decade already, yet many power bricks skip steps between 5v and 20v, so I wouldn't hold my breath here...

PD with EPR can go up to 48V, 28V support is common-ish.