This is a staple that I’ll pick up from Trader Joes:
They have good reasonably priced smoked salmon, organic sour cream (or cream cheese), a GF crispbread, and capers (though reportedly the best capers are the Reese non pareil capers that are usually in stock at Walmart).
You can build them for people like a sort of weird plate of cheese and crackers, or you can leave the ingredients for people to make their own (but keep in mind that the crisp bread and the salmon aren’t really naturally set up for being bite-sized).