Consider the size of the keys when looking at key safes. Mortice lock keys can be too big for some. I had this problem with the first key safe I bought. I replaced it with a Masterlock one and that did the job with either one or two keys in it. To store more than two keys l stuck the least used key on a bit of bluetack to the back of compartment.
If the key safe will be accessed by carers, consider ease of access for them including lighting as well as being as inconspicuous as
possible from the street.