Hey, thanks for the PSU suggestion! I actually tested the power theory by stripping all USB accessories (dongles, hubs, keyboard) and running just the board + HDMI, but it still drops to initramfs. I also know the PSU and hardware are 100% good because DietPi boots perfectly on this exact same setup.
I dug around in the initramfs shell and ran blkid. Here is the output: /dev/mmcblk1: PTUUID="[uuid]" PTTYPE="gpt"
The issue: The kernel sees the raw SD card, but it's completely blind to the partitions (p1, p2). It looks like this specific build might be missing the ext4 drivers in the initramfs, which is why it can't find the UUID to mount the rootfs.
For the devs, here is the exact image causing the issue: Armbian_26.2.1_Radxa-zero3_trixie_vendor_6.1.115_minimal.img (Flashed via BalenaEtcher, verified successfully, and ignored all Windows format prompts).
I'm switching over to the official Radxa Debian image for now so I can finally get my onboard AIC8800 Wi-Fi working, but I wanted to drop these debug notes here in case this is a regression in the recent build.