Using one Sharepoint list to populate dropdown on another

[dg2000r]

Hi

We have a sharepoint list which contains a list of offices such as:

OFFICE| COUNTRY| CITY

Office1 | France | Paris (note there can be multiple offices in one city)

Office2 | France | Paris

Office3 | France | Toulon

Office4 | US | New York

Office5 | US | Miami

We'd now like to have a second sharepoint list which contains:

CITY | SOMEDATA

But when they create a new item in this list, we'd like users to be able to select their city from a dropdown which is populated from the entries in the first list (after having removed the duplicates there) - eg.  Paris, Toulon, New York, Miami

Please can someone please point me in the right direction? I'm not set on technology, so it could be PowerApps, Flow or a combination if needed.

Many thanks