Most of the substitutes are low in sugar but very sweet tasting which sort of defeats the point of eating it if you are a hummingbird.
Suggestion for plants for hummingbirds its best to look at what grows in the wetter parts of Chile and Argentina if you are in the pacific northwest. Here in England we can grow nearly a lot of the plants of the Aruacaria and Patagonia regions so I think you will be fine with your more similar hotter climate.
For example the nation flower of Chile, the Copihue: https://en.wikipedia.org/wiki/Lapageria
would be a good suggestion as it provides an edible fruit, a beautiful flower and is becoming increasingly threatened in its natural habitat.