isn't this what PXE booting is for?
Exactly.
Not only that, looooong before there was PXE on x86, there were other technologies on other hardware that provided, as a standard documented part of the core CPU and boot ROM functionality, what PXE eventually got around to implementing as a "value add" feature.
E.g. lots of DEC VAXes and pretty much every DEC/CPQ Alpha system had a documented network boot procedure, using either an IP network stack or (in the olden days) a DECnet stack. It needed no management co-processor or other untrustworthy stuff, just the standard processor and a standard boot ROM and standard documented network-bootable code and corresponding executables.
The industry has moved on since then, hasn't it.
Biting the hand that feeds IT
