Hello. Since this topic fit to all models of the MNT-Reform, I had decided to post it here.
My proposal is to use instead of BIOS and UEFI something called LibreBoot, with loads the system much faster then the mentioned above, is more customizable and foremost Open Source, with is a big adbentage over the remaining ones
Does libreboot support arm? Last I remember libreboot only support x64 platform. The one arm platform used call uboot.
Update: don’t mind me libreboot do support arm.
Is there some you would get with Libreboot that you aren’t already getting with uboot? I mean uboot is pretty barebones as well.
As far as I had read, LibreBoot supports uBoot.
Additionally, I had read that one of uBoot’s issue is:
“Environment storage is likely dangerously broken”
But… none of the platforms supported by the Reform which are out in the wild right now comes with BIOS or UEFI… 
The thing that gets loaded by each of the supported boards is u-boot (which is FOSS) and even if you swap that out for something else, you would still require proprietary DDR training blobs (which are currently loaded by u-boot).
If you don’t like u-boot, then there is ongoing work to make TF-A + EDK2 UEFI work on the upcoming rk3588. But in any case you will continue to require some sort of loadable blob unless you own the LS1028A and use it either headless or with a PCI-E graphics card.
I had done some research and had found some chip’s on with should be to possible to write the LibreBoot.
It’s worth to mention here that the listed on their website hardware list may be incomplete due leak of enough research from their side.
Additionally, in opposite to others, on MNT-Reform such chip could be easyly implemented (instead of BIOS/UEFI) and it could have a great benifit for the project