Yes! Isopods can be a healthy part of a varied diet for many insectivorous pets, including bearded dragons and leopard geckos. Hobbyists who keep dart frogs and micro geckos love using isopods to add nutritional variation to their standard flightless fruit fly diet.
Considering how widespread and abundant isopods are across most of the world, it's likely that our pets' wild cousins eat a ton of isopods as part of their natural diet.
Isopods are crustaceans. In other words, they're more closely related to crabs and lobsters than crickets and roaches, so their nutritional composition is quite different from feeder insects. For example, we know they have a higher calcium content, which is excellent since insects usually have more phosphorus than calcium. On the other hand, isopods contain a lot of ash - basically, the part of the organism's body with little to no nutritional value.
These differences are why a varied diet is the healthiest - for you, me, and our pets!