If there’s one thing I’ve learned, you can’t have a productive technical conversation based on fuzzy hypothetical options, and shifting objectives.
I can find no evidence that the mobile Navionics application “understands Seatalk”. What may be misleading is that the Raymarine Raytech RNS software, which “understands Seatalk without a mux”, uses Navionics charts. Brookhouse also stipulates the Program iNavx as a requirement for using their iMux combiner, again using Navionics charts. Navionics Mobile supports Plotter Sync which enables the wireless exchange of waypoint and route data. The following link is to a YouTube video by Raymarine which clearly demonstrates what is exchanged.
I don’t share the assessment that the Brookhouse iMux is for “somebody who is starting from scratch.” It was designed, built and is marketed to address the question and requirement you initially detailed…”Is it possible to access Seatalk information on an iPad thru its wifi connection and either