Brunei
When I think of an easy, crowd-pleasing thing to bring back from Brunei, tenunan woven cloth pouch is a good pick because it does not need much explanation when you hand it over. The trick is to choose the simple, well-made version. Small craft items look better on a shelf when they are not too shiny or mass-produced. I would rate it higher when it is locally made, clearly labelled and easy to use at home, and lower when it is just tourist packaging.
Brunei
Layered spiced cake popular in Brunei, Malaysia and Indonesia.
Brunei
Patterned cloth used for shirts, scarves and homeware.
Brunei
This is exactly the sort of thing I like bringing back from Brunei: small enough to fit in a bag, but specific enough to remind you where you bought it. Look for a boxed version with a decent date on it, especially if you are buying it near the start of the trip rather than at the airport. It is also the kind of thing you can talk about when someone asks what you brought back, because there is usually a little story attached to where you found it.
Brunei
I would put Ambuyat sago pearls on the list for Brunei because it is the kind of thing that feels useful once you are home, not just another airport purchase. The best version is usually the sealed jar, tin or packet from a normal supermarket, spice stall or food hall, not the most expensive tourist version. The reason it works is that it gives you a quick reminder of the trip without needing to keep a fragile ornament safe forever.
Sambal tahai is worth adding because it feels like something you actually noticed while travelling through Brunei, rather than a generic souvenir. Tins and sealed products are the easiest version. Fresh or chilled fish is usually not worth the hassle unless you have checked the rules. The ideal version is modestly priced, not too bulky, and good enough that you would buy it again even without the holiday memory.