I'm sympathetic to this argument, and I admire what remains of the anti-war left in Israel, but what would it mean in practice for Western leftists to ally with these groups? For my part, I see absolutely no way of influencing internal Israeli politics from outside.

I should have been clearer. It is not about pressuring only the Israeli government but primarily the US govt. Right now Biden can still argue that unconditional support to Netanyahu is pro-Israel but the reality is that these folks can turn that narrative around. IF they are amplified.