First impressions of "Wallet of Satoshi" are favorable. It is, of course, non-custodial, but it also Just Works™. For my use-case, that's enough.

Swapping XMR to BTC and dropping it on-chain with WoS means sats are available right away, and from there fairly simple to mint Cashu via Ditto for use. So long as I only keep enough of a balance to suit my short term needs and extract any excess to my custodial wallets, I don't much care that WoS holds the keys to the petty cash.