@SlugFestGet the sim and try it out. This is the exact sort of...

@SlugFest
Get the sim and try it out. This is the exact sort of trip flexiroam is made for- two separate networks.
The alternatives would be carrying around a device (ugh) or local sims at BOTH of these places.
Most airports these days have SIM cards on site but there is often a queue and the prices are typically more expensive than a local sim elsewhere.
If you do opt for a local sim at the airport you have to know there is a booth at the airport, pay elevated rates, plus wait for the sim.
Alternatively if you try to buy a local sim in the cities (x 2 I might add) you either pay exhorbitant rates for a transfer or local cab (instead of Uber) or plan bus/train itinerary well in advance with no recourse in event of problems. The difference you pay with flexiroam will be made up in the airport transfer alone (UNLESS you are a very heavy user of data in which case it is probably still best to have Flexi plus local sim).
With flexiroam you seriously just switch your phone on during taxi and it is working immediately. Clear customs, pick up your luggage then get an Uber straight to your hotel. No planning required, no time taken. No wonder the heaviest users of flexiroam are airline staff. Seriously- give it a try you won’t think about how you would go back.