EFI boot failing on new machine

[Paul Ripke <stix%stix.id.au@localhost>]

Finally got around to replacing my 2012 vintage amd64 box.

New machine:
Gigabyte B650M DS3H, AMD Ryzen 7900 12-core, 64GiB RAM

I am planning on installing a recent build of netbsd-10, but right now
I'm stuck trying to boot off a USB stick:

lubuntu: boots
freebsd 14.2: boots
netbsd-current & netbsd-10: fails

Secure boot is disabled, EFI boot device is recognised in all cases,
so afaik I haven't screwed up dumping the images onto the USB stick.
I've also tried a couple of different sticks and different USB ports
with no change.

After the MB splash screen, the failure leaves the cursor in the top-left
corner, and that's it. No response to the keyboard, including
ctrl-alt-delete. Last images attempted were:
https://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/202502210110Z/images/NetBSD-10.99.12-amd64-install.img.gz
https://nycdn.netbsd.org/pub/NetBSD-daily/HEAD/202502210110Z/images/NetBSD-10.99.12-amd64-live.img.gz

I'm new to EFI. How can I debug this? Can I copy the bootx64.efi from
freebsd and use with netbsd? Can I enable some sort of verbosity in
bootx64.efi?

I've tried flipping various settings in the BIOS, but I don't see
anything that screams "compatability" at me.

Help?

-- 
Paul Ripke
"Great minds discuss ideas, average minds discuss events, small minds
 discuss people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.