Welcome to the forum bummm!
In my early years of fixed line fishing I found it so effective for streams that I wanted to see how it would do for lakes and saltwater. I fish for Salmon and Sea Run Cutthroat Trout from the beach in a saltwater “Sound” that is similar to a “Fjord” but generally wider. I use two different western rods depending on what I am targeting. The beaches near me are flats. The inshore “Sound” "surf " is generally wind driven waves or wakes from commercial shipping. But there are strong tides and I like to fish in 8 foot to 12 foot tides where there is a lot of tidal current running parallel to the beach at speeds of ~3-5 knots that moves my fly along like a river allowing me to cover a lot of water per cast. I cast 60’ to 80’, generally in a moderate onshore breeze and strip strip strip strip… All the while the fly is also moving parallel to the beach. If I don’t see a “follow” I stop a little bit past the end of the running line, with a 30’ - 33’ compact shooting head out and recast.
I found trying to use a K-rod and a rather heavy 30’ tapered line side by side against my western “beach rod” and an intermediate or full sink line with the shooting head rather disappointing for inshore salt beaches near me for several reasons. I did a long post about it here. *adding There are a couple of follow-up posts that give some additional insights into fishing the salt.
I found that actual local “Coastal” waters near where I live and in places like Hawaii where there is real “surf” are a whole different game of sight casting to fish or blind casting as far as I can into what is usually a strong onshore breeze and strip strip strip… straight back. Fishing rip currents (fixed line=short casting distance… be careful wading!) that can move the fly and (jigging) off jettys (again be careful in high surf) might be productive.
In summary, fixed line fishing in streams has the advantage of current to move the fly through the water. Karin Miller and her Zen Tenkara Customers would probably disagree but IMHO that’s where the real strength of fixed line rods is.