Honestly though, the dwarf shrimp have different temperature ranges than bettas. Cherry shrimp and bee shrimp do best in unheated or slightly heated tanks (<75 F). Bettas prefer higher temps. Amano shrimp would work and I have kept them with bettas before. Mutt cherry shrimp are pretty dang tough so they could probably deal with higher temps but it's not ideal.
Amanos would be a good choice.
The higher temp isn't an issue. The temp of the water isn't like, hurting them and making them have shorter lives, it's just the warmer the temp, the faster their metabolism is. They mature and reach breeding age much faster in warmer temps, about two months before they're ready to start breeding and producing shrimplets of their own, compared to around six months for a shrimplet to reach breeding age if living in much cooler water. They go through all the same life stages that a shrimp in a cooler tank does. So yes, individual shrimp will live longer at cooler temps, but they'll also take longer to mature, breed and begin producing a decent sized colony.
Once I'd had shrimp for a while and had established a colony, I found it easier to think of them in terms of a colony and complex system, like a bee hive or ant colony, rather than getting attached to specific individual shrimp.