@osiris Haha, thank you. I know there are some pea protein based fish alternatives that taste the part (thanks to seaweed), but the only ones that have made it to my particular rural backwater are the breadcrumbed type, rather than the ones that work harder on bits-of-real-fish verisimilitude.
My go-to for home-made not-fish seafood flavours is chickpeas roughly blended with nori and lemon juice, but that's more a sandwich filling. I've considered making onigiri with it, though.