Another (US, yes, other cultures feel free to substitute your own here) Thanksgiving. I don’t really enjoy turkey, I have food issues anyway, feasting is very conflicted.
Then, there is the enforced extended family togetherness, the clueless rightwing folks carrying on vs the suffering vegans. Everyone expected to be happy. This is almost beyond cliché, but it’s real, happens every year.
I can relate to OP. If I skip the holiday, I’ll hear about it for months after, but if I go I spend the whole time counting the nanoseconds until it’s over. Unless you are willing to go NC, there are no easy answers.
I plan distractions during the day to get me out of the house. Go for a walk, find a quiet room to hide/recharge in, etc. Last TGiving, as an experiment, I went into another room to see how long it would take for someone to come looking for me. They never did and I had a nice quiet hour.
Make a plan for your mental health and work the plan.