You can read the draft specification for NUT-26 here:
https://github.com/cashubtc/nuts/pull/300
You can also play with P2BK (though don't be reckless).
P2BK Lock Tokens with Cashu NutLock:
https://nostrly.com/cashu-nutlock/
P2BK Unlock Tokens with Cashu Witness:
https://nostrly.com/cashu-witness/
or Cashu Redeem:
https://nostrly.com/cashu-redeem/