Those already exist =)
https://www.retrorgb.com/freecalrec601-dvds-for-calibrating-crts.html
I see. Well i have no current version like that, it would have it's own set of limitations and options, since it would be bound by the DVD format. But some of the other calibration DVDs out there do offer geometry and resolution patterns, like AVIA and DVE.
Yes, they are only 480i of course. DVD can't do 240p. I recommend you try them out, they might do what you want.
MiSTer FPGA is another great portable option for testing via RGBS or component if that is what is to be tested.
I used to take a Dreamcast for those =)