Closest in Taste Replacements for Oyster/Fish Sauce?

Hi all. I've been getting into Asian cooking recently and my kids are loving it, a great way of getting vegetables in them! The problem is that my wife is allergic to seafood (both shellfish and fish) so all I've been doing is replacing it with whatever I had to hand, often just soy sauce or tamari. Searching around this sub Reddit I've seen a lot of suggestions for replacements from hoisin sauce to vegan alternatives. What I was wondering is, is there a brand (available in the UK) that gets closest to the flavour profile of oyster sauces, and same for fish sauce? Obviously Asian is a wide variety, so it's predominantly Chinese with occasional forays into other countries cuisines. submitted by /u/ScoffAtHistory