Fedimint and cashu are fiduciary media, aka custodial money warehouse certificates.
Discussion
There is a place for trust and community in a decentralised world.
In fact it is a hard requirement to achieve any resemblence of scale.
Depends what you mean by scale, small and replicable can also be at scale.
Scale of Bitcoin as a money, ie most liquid media of exchange.
Could they be legally classified as "securities"?
If so, you are selling Bitcoin/sats in exchange for an issuance, a taxable event (and subject to regulation).