I think the problem is that Chromebooks don't have DVD drives or any significant amount of their own storage (in which case you could store ISOs and mount them)

I think the problem is that Chromebooks don't have DVD drives or any significant amount of their own storage (in which case you could store ISOs and mount them). And SD cards are pretty expensive if you only have one movie per card, because while they're cheap per MB, they only come in huge sizes these days.[1] A USB angle adapter and a judicious use of 3D printing and/or sugru and/or VHB tape might allow an optical "undercarriage" though! A Framework laptop with those nifty expansion slots might permit something unconventional like some kind of key-slot/punchcard/unique-MAC-type EEPROM/RFID reader, but the OS won't be ChromeOS. And that's really getting into the "not because it easy, but because it's there" zone! [1]: But i have just discovered that you can buy "unfinished USB sticks" that are just the little black inserts with the flash in them for £1 each for 8GB on AliExpress (cheaper than the same SD cards and less fiddly), which is big enough to get a DVD ISO or BR rip with some massaging onto! (128MB is 50p, so an indirected method would not save much money). Probably very junky chips but the write-once and read-slow use case would probably not really care much.