I wonder if a hybrid approach between disposable and "keep cup" could work.

The "default" takeaway option could be the short-lasting paper cup.

For car, office or just comfort, you could have a squashy, silicone (stands high temp) outer that would usually only need to be cleaned if the inner cup fails.

A silicone shell with disposable inner would work well for me, at least. The shell would rarely need to be cleaned and can be easily pocketed.