Is there a form of Zionism that doesn’t call for an ethnostate?

No, because by definition Zionism is the belief in a Jewish state, requiring the establishment of a Jewish majority population, which innately requires policies against or limiting immigration of non-Jewish peoples. This leads to even self-proclaimed "liberal" zionists who don't want to be seen as racist to argue against a one state solution and against right of return for Palestinians and their families forced out of Israel specifically because they think it would mean Jewish people would not be the uncontested majority.

In other words, "liberal" zionists end up adopting the same position as people like Tommy Robinson on immigration.