M-DISC [0] will probably cover most of the scenarios. It's still expensive, though.

[0]: https://en.wikipedia.org/wiki/M-DISC

I'd heard of those but never looked them up, always thought they'd be super expensive. It's about $40 for a drive that can write them and $13 each for 100GB media. That's pretty reasonable for durable storage.

Yeah, normally it's not expensive, but since market for these discs are so small here, the prices are at exorbitant levels for M-DVDs. M-BDRs were unavailable, but they are available for reasonable prices, as I just checked.

I have drives which can burn M-DVDs, but I'd need an M-BDR drive. The ones I have doesn't support M-DISCs.

Yes. And it doesn’t have to be titanium per se. Cerabyte is trying to use ceramic. Even rocks might be good enough.

Nasa preferred gold (more specifically copper plated with nickel and then plated with gold) https://en.wikipedia.org/wiki/Voyager_Golden_Record

To be fair, that's not simply an archival disc, but also something explicitly intended to be readable by intelligent life elsewhere in space. The encoding of data was optimized for simplicity above all else.