You will get harassed by Zionists that call you fake jews, tokens, and antisemites. This will include both Jewish people and non-Jewish people.
You will also face severe pressure to not associate with Zionist Jews at all. If you do, you will be accused of being a Zionist and then harassed again.
Assuming you manage all that. It's going to be a small instance. There aren't that many Jews on Fedi, and there are fewer Anti-Zionist ones plus allies. At which point for things to be interesting you'll want to connect to other instances with compatible politics. You will face lots of pressure to look the other way on antisemitism or be defedded. And remember this would be a small instance so it's easy to defed.
At which point, many of your members are likely not using the instance as their main and get better safety guarantees just being on a larger instance.
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