M-discs either DVD or Blu-ray works well[0]. It uses a mineral layer rather than the typical dyes and pigments to be more robust.

They are writable and readable by most modern standard drives.

The claims I generally see is 100 years for standard storage, 1000 years for archival storage.

https://en.wikipedia.org/wiki/M-DISC

If you need tons of storage, I actually do think you should check out LTO. You can buy LTO-6 tapes for about $10 if you get a bunch at a time, and each is about a 2.5TB. On a good day you can find external SAS LTO-6 drives for about $200. LTO tapes are generally rated for decades of use so they’re pretty durable.

Nowadays on Linux you can very easily mount LTO tapes like any other drive using LTFS, so you don’t have to become some hyper-expert with tar.