DH is a nightmare to buy for - he tries to give ideas but he'd be happy with a big bar of chocolate.
But, over the years, I've learned to go for day's out.
So this year it's a theatre trip (if the theatres remain open...)
The year before last it was a gift voucher for a chain of cinemas so he could pick the film. Enough on it for the three of us to go together or for him to go three times if he preferred to go alone, plus a bit for a cola etc.,
The year before that it was a trip to the Shard on the week after Christmas when I knew he was off.
And the years before that I got him a ticket to see Question of Sport live with the previous year seeing a comedian he likes.
If he likes comedy/drama or whatever, it's worth a trawl through the local theatres or bigger city ones. There's so much usually on from plays to musicals and everything in between.
Or if he's into heritage you could get him membership of NT or something similar?
I've also bought DH books on gardening and a set of personalised tools - like trowels. I got him a plant trough with our names on it from Etsy which went down well and he did a lovely display in them.
And I've bought him flavoured coffees too as he loves his coffee!