It is tends to be Irish Republicans who are are pro-palestinian to the hilt.
Whereas many Ulster Unionists show solidarity with Israel and occasionally even fly the Israeli flag together with the British and Northern Irish (Ulster) flags, many Irish Republicans prominently fly the palestinian flag together with the Irish tricolor.
On "bonfire night" in some Irish Republican areas in Northern Ireland, the Israeli flag, the British flag, and the Ulster banner are placed on a large pyre and burned.
https://www.youtube.com/watch?v=e_xbwL_fcOA