There are natural supplements one can take to reduce the excess DHT being released - if that's the cause, that could help prevent further hair loss.
If it's thinning at the crown, and the hair loss is progressing slowly (over years as one ages) then he could also try a coverup product - I forget the name(s) but it's basically coverup a man puts on the scalp, which is the same color as his hair, and it makes the hair look a lot thicker, works especially well for the crown. Of course that is not preventing hair loss, or treating the cause, but it will make his hair look thicker, and it's immediate.
I think so far only Minoxidil has proven to be of any use, and for only some men. And yes, you do have to keep using it. Why don't you suggest he go see a dermatologist, not some flaky hair-loss place, and talk about the options?
A lot of guys do learn to adjust to the fact that hair loss is baked into their genes, and rock the very-short or bald look. I'm thinking of well-known guys who look great, like "the Rock" Dwayne Johnson, and Jason Momoa who just chopped his long locks, Bruce Willis in the Die Hard movies, Vin Diesel, Jason Statham. Sure, your husband is probably mourning the loss of what he has counted on before and associating it with youth gone away. But he could be stepping into a new studly phase if he tries.