> I don't know why this keeps coming up-- joining the EU does not require adopting the Euro.

The EU website disagrees:

> All EU Member States, except Denmark, are required to adopt the euro and join the euro area. To do this they must meet certain conditions known as 'convergence criteria'.

https://economy-finance.ec.europa.eu/euro/enlargement-euro-a...

Because domestic UK politics wouldn't allow this to pass on technicalities, I mean haven't you learned anything from the build up to Brexit? It would have to be explicit to be palatable, not some technicality that we effectively want to play ball on the Euro, but never really do... Hell, even from the EU side I'd want a honest decision, not political illusion.