Salut @Francois
If you are looking for a Free & Pro Map solution to replace GMap, there is an open one that may suit your needs or your clients needs.
Plus you can help improove the Maps yourself whenever - in fact - it covers many areas where GM does not send its Car/bike or whatever… 
Its a feature I ve requested since its the only one available in some areas (Yes G does not map the whole globe…)
support Adalo OSM request here - if you like free stuff 
more info on OSM 
(i ve myself contributed to Maps creation in some south America areas uncovered by GM)
https://wiki.openstreetmap.org/wiki/List_of_OSM-based_services