Welcome
@littledog. You sound like a loving grandmother. That's great!
Your husband sounds a lot like "yer dad". Which is to say not YOUR dad, but like, the concept of the stereotypical "dad". Kinda conservative, older white guy who doesn't mind different things as long as they're not public or in his life, as if something like who you love and who you are could ever be under wraps.
I know you've probably done a lot to try to convince him and I bet your grandkids know it. I think with people who do really want the queer people in their life to be happy, the best tact to take is to remind grandpa that learning and using the correct terminology or just being supportive of them is suicide prevention. Suicide rates for trans folks plummet when the people in their life use their chosen names an pronouns. Similarly depression and suicide rates drop for lgb folks when those needs are also respected, even if it is something as simple as correcting language. (like if a girl is a lesbian saying "When you get married some day your wife/partner...." instead of husband.
That might be a way the slowly bring your husband around that he's more responsive to. But kudos to you for doing the learning you have and loving your grandkids.

Wish everyone here had a grandma like you!