please add eMMC to the board so the OS and filesystem can stay there for robustness, SD card is fine to store data but that’s about it. 4~8 GB eMMC is more than enough, in fact anything above 16MB(e.g. flash) will be great(for openwrt,yocto etc).
really like the 2 CSIs, which is a great selling point comparing to RPI4 etc.
In another thread, I suggested an eMMC slot same as what Pine64 uses. This is a connector on the main board to allow a small, (postage stamp sized), daughter board with the eMMC chip on it to be installed.
This would allow the user to either choose SD card as the cheapest option. Or buy an optional eMMC card, (of various sizes).
In the case of Pine64, they make 16, 32, 64 & 128GB eMMC boards. The larger ones are not cheap, yet still reasonable given their size, speed and reliability. Their is nothing stopping Beagle, or another vendor, from making a 4 or 8GB board, which would be cheaper.
Samsung even makes a 256GB eMMC chip, though no one I know makes it into a Pine64 compatible daughter board.
I am agreeing that a slot would be best / optional for eMMC, I do use 64GB eMMC on a rock64.
There are few issues with that, including at least 2 types of physical connectors, eg, my nanopi-k2 has a socket with pins for emmc, but odriod-c2 and pinebook og have a snapon connector. For the latter type, not all boards are necessarily compatible with a given device, where the vendor declares something like “compatible with red, orange, and blue emmc cards, but not the black ones”.