Shamir Secret Sharing
OK, since we're pitching our SSS implementations here in comments, I welcome everyone to check out BananaSplit, https://bs.parity.ioNot sure about year 2023, but at the time I wrote it for my previous employer there was nothing remotely usable for regular user.Thus, BananaSplit.
It doesn't allow you to specify many parameters (just the number of shards, and then requires 50%+1 to recover); aimed at printed backups (generates printable full-page QR codes, while asking to copy a decryption phrase to the pages by hand to avoid an "evil printer" attack); and takes the concept of _portable web app_ to its extreme, being a self-contained single html file which requires you to save it locally and open via file:// protocol for it to work.Disclaimer: while being in use for years, the code had never seen a proper independent code review; there might be bugs, despite me trying to minimize their impact by design, and using only reputable (and pretty minimalistic) JS primitives.
If you want to check out the sources yourself before using, of course those are available under  GPL at https://github.com/paritytech/banana_split/