Adding Marine Charts

I'm looking for a way to add USA based nautical charts to the Fenix 5 plus. I currently own a Garmin G2 Vision chip and a Bluechart CD. I have been told that both these charts are not compatible with the watch and we must purchase the newer G3 Charts. These charts cost $350 which seems very high just to get a basic chart on the watch. There is also the possibility that the chart will not even fit on the watch as it is very large. The G3 charts include items such as photos and POI's that would not be useful and just take up memory.

I did find a YouTube video from 2017 showing Garmin charts on a Fenix 5x but there isn't any instructions as to what Garmin charts were used and how they were installed.

Also why are there "marine" settings in the watch if there isn't an ability to add marine charts and actually use the settings?

Can someone here, or a Garmin rep, confirm if all this is true or advise us on how to add simple marine charts for kayaking or other water navigation?