This would be perfectly acceptable at my work.
A grandparent is considered a "direct relative" and the starting point is 3 days, where 1 is the funeral.
However, it is also line managers discretion so we would be expected to have that conversation, not just not go in. Discretion also can mean more time.
When my Grandma died, I had a day where I did the mad dash across country to her bedside on a Friday. Then she died in the night Sunday night. I did an hour or so handover that day, then had Tuesday off and worked a couple of hours each day for the rest of the week. She was in rented accommodation and we only had a week to clear her flat so we had a lot to sort quite quickly. My boss was clear that he didnt expect me to work that week at all but the balance suited me. I then had a day off for the funeral a few weeks later.
In comparison, when my other Grandma died during covid I took the rest of the day after I got the call and then half a day for the funeral as it was remote. I worked in the morning more as a distraction than anything. This death was more expected though so I'd done some "pre grieving" of sorts.
Sorry for your husband's loss and I hope his work are compassionate.