If you keep the plugin open all the time (for the period that you need to receive changes), the only method would be to check for changes through polling. There is no built in method to just “listen to all changes in the file”.
Thanks fro your answer, I thought about that, but the point with this approach is, how can you continuously poll a figma file from a plugin? what could be you target to poll and somehow get updates?, I am also a bit concerned about the performance of continuous polling.