That was the problem for me too.

There are many implementations of Shamir Secret Sharing out there, but they're all idiosyncratic and impossible to vet unless you have a background in cryptographic security, and like you said nearly all are not actively maintained.

The types of things you would go to the trouble of Shamir Secret Sharing, are also the types of things that might surface decades later (e.g. crypto keys). Imagine going on a treasure hunt to retrieve 2 shards, and then needing to go on an additional internet archaeological hunt for the specific GitHub repository used to generate the shards.

Unless someone solves this issue, I can't see Shamir Secret Sharing becoming any more mainstream.