I'm a very similar way as you wrt food, but not the social pressure part. I don't like eating in professional settings (eating is messy, for one), so I will usually eat alone beforehand and then only order something very small and light (or even just beverages) at the meeting meal. The social pressure thing I find to be easily deflected.
Same goes at bar/drinking events. I don't like drinking alcohol but everyone seems to report perceived pressure to drink alcohol at such things. I haven't found drinking nonalcoholic things to be the big hassle others claim it to be.
I think people build up the expectations more than they actually are in reality. Most other people don't really care that much what you're eating or drinking, if they are eating or drinking what they like.
WRT drinking, it can take a lot longer to build trust without the shared alcohol experiences. You’re correct that there isn’t direct social pressure, but you end up getting left out of “after-event” drinks as well.
I noticed these things when I had to go on a strict diet with no alcohol for about a year. You might argue that nothing important happens during non-formal events, but that’s a big mistake.
But we spoke with the server, and she found me a dish from the prix fixe arrangement that I could eat, and spent the night just making sure there was always some of that dish on the table.
Everything went better than expected. Sure, I don't have to be worried about death from being exposed to food I won't eat, but I could've called ahead, and would've, if the stakes were that high.
I guess all that's to say: good restaurants are pretty accommodating, even when they aren't doing the normal menu thing. It's really not that crazy.