I have rescued baby birds. I also fed them moistened dry cat food with a pair of small, clean needle nose pliers. Baby birds opened their mouth for me and I put each moistend (till soft) kibble gently in the back of their throats. Don't think there is much risk of them aspirating, unlike with chickens because the chickens won't open their mouth for me so there is more forcing / struggling.
Keep baby warm. Feed every hour during daylight hours, if they are doing okay you don't need to feed them at night, but if weak or not doing well, I'd feed a few times in the middle of the night.
The challenge is always reintegrating into the wild, for that I would take them to a rehab facility to get them used to fending on their own unless you have a big aviary.
good luck!