Please, is this an unlocked device that one can use to boost any existing wifi connection?
Are you talking mesh or Access Point? This might be same to be setup as AP mode. You’d probably have to search the manual
It’s not a cell phone, so it can’t be locked to a service provider, and it’s not a cable modem, so there are no service provider compatibility issues. It takes the data stream from your cable modem (or other Internet source) and routes connections to your devices - computers, cell phones, wifi printers, wifi TV connections, ad infinitum.
I suspect this question is being asked by someone who currently has an ISP provided data receiving/routing/wifi “all in one” device. Most of the cable services push for subscribers to rent one of their cable modem / WiFi router combination units (often referred to as you “gateway device”) (yes, looking at you Comcast) and if the subscriber has little technical expertise, it’s probably a good idea. That being said, a little basic internet / equipment functional knowledge can free you of those rental fees, and also give you a more user configuration possibilities, as well as a better upgrade path. My Docsis 3.1 cable modem cost me $79 (1-1/2 years ago) even though it can handle a 6-7gB internet connection - far faster than any provider around here, even on fiber - and my AX5400 triband router was $99 (factory rebuild and they were still getting $179 for “new” at the time) can handle more devices than I could ever want to own and at an average speed that leaves them waiting on the ISP, not the router. My ISP currently can only provide me with 500mb service and the router could do that to each of my 6 owned / connected devices concurrently. Ready for GB service? No, ready for 10GB service!
Quite interesting… You dropped knowledge and wrapped with Flex 
drop moment of the morning, thanks for the smile 