Per your advice I picked up a pretty cheap/small drive on eBay. Thank you very kindly for the advice. Now running 134.0.0.0.0.
If anyone else state side ends up in the same boat, I did end up reaching out to OWC support. As usual, they were very helpful and accommodating. They offered to ship me an OEM blade for nothing (with just a simple credit card hold). I opted for the eBay deal because it was so cheap and I'd never have to fuss with it again. It's nice to have around, I suppose.
Buying a 32GB 12+16 AHCI blade is the way to go if you have a really old pre-NVMe BootROM version, if you already have a newer than MP61.0120.B00, where NVMe is supported for the first time, a NVMe 12+16 blade like the Apple 12+16 blades based on Samsung SSPHOTON controller will work fine.
Apple will continue to send BootROM upgrades in the near future. While nowhere near BridgeOS Macs cadence, Apple has been sending frequent updates for MP6,1 BootROMs.
Apple made six MP6,1 BootROMs in 2019:
EFI version: | EFI build date (not the release date): |
128.0.0.0.0 | 1812191437 |
129.0.0.0.0 | 1902141849 |
130.0.0.0.0 | 1904121119 |
131.0.0.0.0 | 1905251553 |
132.0.0.0.0 | 1906132222 |
133.0.0.0.0 | 1907241309 |
134.0.0.0.0 | 1912181758 |
Besides the usual DXE corrections that Apple issued in the last two years, like the frequent APFSJumpStart improvements, Intel will have to correct Ivy Bridge microcodes sooner than later and Apple will follow up with new BootROMs for MP6,1.