FEATURE REQUEST: Make sensors available offline

[Vato9394]

Sometimes, The websites (API's) of the waste collectors are down.
When we restart home assistant in this particular period. no sensor is available in this integration since no connection can be made.

Is it possible to make some sort of "fallback"? Store the sensors in an offline db.
Something like keeping the last known values and printing an error in the log ex "could not make connection with waste collector api, currently working with offline sensors, will try again in 12 hours."

Its just an idea, I don't know if this is feasible/relative easy to implement.