Getrandom(0) on the latest Linux kernel, assuming the computer is used for a while first (as there's no real way to figure out how much entropy is "enough") is

Getrandom(0) on the latest Linux kernel, assuming the computer is used for a while first (as there's no real way to figure out how much entropy is "enough") is probably fine for actual one time pads. I think it's very unlikely that any future attacks could pwn ChaCha20 (and Blake2s) to that extent. You would have to figure out were you were in the stream, and with what key (possibly multiple keys). That's pretty close to zero information in cryptanalysis terms. You would need to make sure the computer generating the pads, as well as the printers, etc. Are well shielded and not emitting usable EM information, don't store the pads in any way, and are not compromised beforehand in some way, such as a supply chain attack.