I can't wait for a modern system with an open firmware. Just so that there would be any hope for bugfixes outside "works for (default configuration) Windows".
Surely, open firmware could skip that and boot faster - if vendor would allow an escape hatch from the "secure boot" hell. But why would they expend effort on something 99.9% of users don't care about, and give up free ads in the process, too?
I haven't used the most recent AMD server platforms, but on earlier Epyc generations the memory training and PCIe link training were noticed durations but measured in seconds, not minutes. Turning on debug for the PSP could turn this into minutes but would also show all the results of the memory training sequences. The memory testing would take minutes but was easily disabled to reduce the boot time. Has this changed in the newer Epyc generations?