How to change time unit of measurement on a sensor with expiration date?

I have a health sensor that lasts 15 days, connected via the LibreLink integration.

One of the entities supplied is the sensor’s expiration date timestamp, which is listed as a date+time.

When I put the expiration entity into a tile, it simply lists the expiration time as “Next week.” I would prefer to see this countdown in days, or hours, for the whole duration of the sensor life.

I’ve tried putting in a “unit of measurement” entry in the yaml but this doesn’t seem to be the right approach.

Would appreciate any help.