Can supporters donate in Israeli Shekels (or any other currency other than USD)?

Yes.

Anyone in the world with a major credit card (and/or PayPal account, in the case where you choose to be fiscally sponsored by Jewcer) can donate to your campaign. Think of it like they are buying something on an online store in the USA. The prices are described in USD, the payment is done in USD, however, the charge to the buyer (“donor”, in this case) depends on their credit card (or PayPal account). If its an account in Shekels, their card issuing bank will perform the exchange automatically based on the exchange rate of that day.