The CB3-431 is device name EDGAR. You'd most likely pull the write protect screws and flash a UEFI payload into the firmware, probably using Mr. Chromebox's tooling and payloads. Most modern Chromebooks boot Coreboot with a depthcharge payload, and it can either be coerced to boot something different with a lot of effort, or easily swapped with a Tianocore UEFI payload to make it behave like a normal PC. Once flashed, it's an ordinary Braswell generation PC with 4GB of RAM and 32GB of storage.

The S330 is an ARM machine built on a Mediatech MT8173C. Installing normal Linux on ARM Chromebooks is substantially less well-established, but often possible. It looks like those are doable but you won't get graphics acceleration, and the bootloader situation is a little klutzy.

Of the two, the CB3-431will be easier and better documented to bend to your will.

The major limitation with Chromebooks is really just that there isn't much onboard storage, so you'll want to pick reasonably light software (A distro where you pick packages on a small base install or at least a lighter spin will be preferable) and avoid storage-intensive distros (eg. Nix or the immutable-core-plus-containers schemes whose packaging models have substantial storage overhead are probably unsuitable). You may have a little hassle with sound because many Chromebooks have a goofy half-soc-half-external-codec sound layout for which the Linux tooling is still improving - a pair of annoying PipeWire and Kernel bugs that sometimes cause them to come up wrong and spew log messages got fixed last week but aren't in a release yet.

They aren't fancy machines, but hacked used Chromebooks make great beaters.