For consumer accessible long term storage…

Large amounts (many TB), look at LTO tape, 10-30+ yrs depending on storage, but you have to keep drives alive. Second hand LTO5 (1.5 TB per tape) run around $300 per drive (you’ll need an SAS card as well), tapes are pretty cheap and last many rewrites. You’ll want 2 drives of the same manufacturer and type (that read each others tapes, finicky) and perhaps a third that doesn’t work for spares.

Smaller (100GB) amounts Metal, probably good for 100 yrs, not organic dye, that shit self destructs in 5 years, Bluray-XL disks. Good for photos, text and probably audio depending on how much. Unfortunately there’s only one disk manufacturer left (so monopolistically expensive) and no drive manufacturers currently. So 2+1 drive protocol applies.

Long term data storage sucks (yes I did the research). There’s a couple of techs like the article describes, I like the quartz one best, millions of years, but the chance of seeing them mass produced is low, built in obsolescence baby, it’s an income stream.

For mere mortals a 3-2-1 backup strategy using spinning rust HDD is still most practical, and still expensive and cumbersome. If you’re willing to trust online backups (encrypt at home with like cryptomator) are not uneconomic, given the easiness, but you may want two for safety.

Editorial : You’ll own nothing and hate it.