Unless your battery was previously replaced, it probably is not an AGM. I suggest you take the cover off & verify (unless you have already done so).
I certainly would not believe your dealer.
YES it:s annoying but probably happens to everyone with a Mav Hybrid but in most cases it always starts & won't leave you stranded. . I regularly trickle charge mine in NJ's winter climate & just got used to it.
Ford does have as an H4 AGM Battery used in the Corsair & the '25 Maverick but...