We have wifi setup in the house using the providers router. We are wiring Cat5e through conduit to our pier which extends far past the range of our home wifi network. At the pier we want to use a router/extender/hotspot to hopefully allow connection to the same wifi network. The home wifi network has a SONOS system installed. The goal is to have wifi at the pier and a connection to the same SONOS system. How do we do this and what are the best products to accomplish?

Pretty much any wifi router can be used as a wireless access point. That puts you on the exact same network as if you are inside your house so all should work like you want.