I think FOA is a grouping of operators doing business in Canada. In the past it has been impossible to link up and connect with them on advocacy or safety topics so I go by what I've heard about them so far.
They are effective in protecting their business assets in an increasingly harshly and double left & underhandedly regulated Canada. As you may know, quite a few very highly publicized accidents have killed a lot of people over the decades, causing TC to more or less run around like a chicken with no heads about seaplane egress as well as passenger briefings and flotation devices. The group is seeking to advocate for itself through positive perception, by adopting voluntary/ more than regulatory compliant safety rules enhancing safety through the use of flotation devices, passenger briefings and pilot training with its associated members. I am not sure they take individuals as members.
In the past I have constantly worked to connect our membership with other groups and associations (heavy focus on advocacy & safety), however the laws of exclusivity rule the show. Groups who are responsive to email and looking for mutual networking opportunities with our group of misfits are listed here
The most help in your endeavor (I suspect you're looking for more information sources) is likely going to come from the various forums on seaplane flying and its useful participants.
Hope this helps.