

If this is a real problem you have, and not just a thought experiment, I think rather than burying the data on some unreliable medium, your best bet is to just pay someone to store it for you offshore, away from the dictatorship you mentioned.
There are plenty of consumer-grade cloud storage services. I’m sure there are more niche ones specifically for long-term archival as well, which would usually be cheaper per bit, per-year, if you don’t need to access the data regularly.
Yes that’s true. There may also be issues just with getting money out of the country to make the required payments to the storage providers. Either due to local restrictions or international sanctions.