Just hold your ground and keep reading your book, eating alone etc. If someone enters personal territory, shut it down by being honest "I don't want to talk about that" and move on. Resist peer pressure and be who you are, it's the same as it was in school.
Also, talk to your coworkers (I know it's hard) about whether they think it's appropriate. You have an impression they're on board with this level of "intimacy" but it's possible they are just going along to get along.
If persisting doesn't work then it's probably time to find another job. Plenty of workplaces out there that just want you to do your job and no more.
HR is definitely not on your side either, unless you can point to specific violations of policy. They exist specifically to cover their own ass, not to actually make your life better.
Israel is currently genociding Palestinians under a Democratic president, they didn't need Trump's approval for anything. The bulldozers are already running, the people are already having their lives destroyed.
Again, I voted Harris for harm reduction, so I see your point about Harris possibly being better for Gaza in the long run, but it's not "kill my friends now" or "kill my friends later" it's "kill my friends now" or "kill my friends now and maybe, just maybe, stop sometime around the midterms when it's politically convenient and only if Harris doesn't need to keep getting the fascist vote". I don't blame Gaza voters for looking at that choice and holding out for what they really want, which is "stop killing my friends now".