What I was looking for actually was the same tool as the Ian Coleman's
Shamir39 tool, allowing to get shares into a mnemonic format from a BIP39 seed also in a mnemonic format but I understand it doesn't exist with SLIP39.
-snip- I don't want to rely on an isolated tool.
Yeah, it's a good thing that the big red warning above iancoleman's shamir39 tool is hard to miss.
It's sad they still haven't standardized a protocol allowing to do that.
Bad new is: I think it's impossible to create a standard for this without changing BIP39.
The main reason is it's nearly impossible to get the mnemonic back from the seed since it's a product of 2048 rounds of HMAC-SHA512 algorithm which is considered one-way.
And changing a standard to implement another standard defeats the purpose of "
standards".