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Scrit (also referred to as Scrit1), which is referenced as "prior art" for Fedimint, has methods for "half-offline" (i.e., only sender online, or only recipient online), and offline (i.e., both offline, and could be done via paper / QR codes even).
"Scrit: A distributed untraceable electronic cash system" https://github.com/scritcash/scrit-whitepaper/blob/master/scrit-whitepaper.pdf
The Fedimint homepage also refers to "Scrit2" with having "receiver- and sender-initiated half-offline transactions".
And along these lines:
Transferable E-cash: A Cleaner Model and the First Practical Instantiation https://eprint.iacr.org/2020/1400.pdf
And there are a number of redeemable code / voucher / etc approaches, including:
LNCash https://ln.cash/how
Satscard, is like an OpenDime where it can be passed person-to-person, offline.
But with satscard the funds can be spent, and then a new address generated. That can be done sequentially for a total of 10 uses: https://satscard.com/faq
There are other approaches with other technologies:
Between a Rock and a Hard Place: Offline Use in CBDCs https://www.progressoft.com/blogs/between-a-rock-and-a-hard-place-offline-use-in-cbdcs
Blockchain side implementation of Pure Wallet (PW): An offline transaction architecture https://www.sciencedirect.com/science/article/pii/S2405959521000928