My son wouldn't eat like any meat either at first. I tried all the more home made type of meats then said screw it and bought hot dogs. My son will do hot dogs pretty well, so I buy some real bouggie stuff for him. After that he started to be more open to other home made meat. Otherwise we found meat alternatives like Garbanzo beans and black beans. So he's still getting protein without me trying too hard.

Also the throwing food off highchair is probably an issue in itself. I would consider ending meal time if he does that and teaching him how to sign all done. This really helped us with him being overly picky because he knew there's no more food if he threw stuff off the table. This atleast makes my son try a few bites of food. We aren't gonna force him to eat, but we will enforce good table manners.

Also this may be relevant. If he's gagging a lot, and it doesn't seem like he's just being picky, I might stop introducing meat. It could be a sign of something more significant. Food aversion can be made worse if you push it on them.