Hello again,
I'll explain below, but TLDR is between the accessibility requirements and the weird nature of the hardware, this is, in no uncertain terms, not the laptop for you. I would highly recommend waiting, at least until the rest of the K1 SOC is fully upstreamed; the wiki page for this I will link again here:
https://github.com/spacemit-com/linux/wikiFirstly, you ***cannot*** use a custom kernel for this device, at time of writing. The hardware developer has a custom kernel that you *must* use for this device, v6.6. While there is work in progress, a newer kernel that is not distributed by the hardware developer will not work.
Next, let's talk u-boot vs UEFI. U-boot requires a lot more than UEFI, as has been mentioned previously. However, there is a lot more information hidden in that statement than you might think. For example, you can't just move the dtb file to the right location. The "dtb" extension stands for DeviceTree Binary, and is directly tied to the kernel version being run. Simply moving the binary into the right location will cause a version mis-match and cause the hardware to not boot properly. Also, with the version of U-boot the DC ROMA II uses, the entire boot stack is stored on the storage medium (be it SD card or NVMe). This is opposed to UEFI, where you just have flash on the motherboard that is smart enough to reach out to the storage to find your bootloader to get the process started. If you look in the installer ISO for Debian, in /boot/dtbs I believe, it lists all the compatible chips, and SpacemiT is not in there. Until it is, the Debian ISO will not work, and given the pace of the SpacemiT crew, I'd hesitantly say expect that to be added in Forky.
To reiterate, simply using Debian Trixie on this device at this point in time *will*. *not*. *work*. The standard Debian kernel does not support the hardware yet, and the SpacemiT kernel you will likely have to rebuild from scratch to get the modules you need for accessibility purposes running, which in my experience is *very* hit or miss getting it to boot afterwards.
I own this laptop, and as a person who is lucky enough to not need any accessibility settings, it is frankly a nightmare to use in it's current state. Simply running system updates is not an option, and I've had to completely reinstall the operating system on mine several times because I forgot. I've tried off-and-on since I bought it at least a year ago, and it's currently gathering dust next to my other K1/M1 system while I wait for the upstreaming effort to finish. Even after the CPU gets upstreamed, owners of this laptop will probably need to use DeepComputing's custom ISO while Imagination Technologies (the GPU vendor) gets their act together and finally merges their changes to mesa into upstream.
I would highly recommend reading through the issues in the DC ROMA II Github page (see here:
https://github.com/DC-DeepComputing/DC-ROMA_Gen2_LAPTOP_K1_RV-L2A ), just to get a sense for the state of the device as a whole. It's clunky, it's not ready, and it's largely been forgotten by DeepComputing as far as I can tell while they figure out their Framework Mainboard endeavour. The JH7110 SOC is kinda the only good RISC-V chip to recommend right now for anything outside the absolute most niche cases, because it's been almost entirely upstreamed, and therefore is supported by the Debian installer natively. RISC-V is a really cool technology, and I love it a lot, but the hardware ecosystem right now is about the same as the Raspberry Pi 2 was when it came out, and I mean that both from a software support standpoint and from a hardware performance perspective.
To be perfectly frank, if I could talk to my past self, I would say to not buy this laptop and save myself the migraines. In a few years, it will be better, but the hardware barely runs on the hardware manufacturer blessed distro images. The fact that anyone tried to cram this chip in a laptop is a testament to the arrogance of man, because a laptop appeals to normal people, and this laptop is at best a marketing stunt to drum up good PR for RISC-V on the whole.