I ran my US 110v boat on 240v in the Middle East without any issues.
I permanently installed a Victron isolation transformer and it did the job well.
AirCon - many air-condition systems runs on any frequency. But you will loose 20+% of the nominal capacity going from 60 to 50 hz as the compressor
turns slower. I did not have any issues with my old Dometic Aircon (as in production year 2008)
There was talk about brushless DC motor
compressors which would remove the issue but I don't know if any have made it into production. There was also talk about Inverter based compressors. There is a new Dometic Turbo range that is open to both 50/60 Hz from "factory" but I can't see if they solved
by DC Brushless or Inverter based operation.
Some (not all) microwave ovens will work
. Most resistive loads will work
(oven/cookers) but check labels and talk to an electrician.