There are thousands of old funky track houses across the entire San Francisco Bay Area and Silicon Valley that have never been updated or renovated in any shape or form, and they're really expensive and so buyers can't afford to remodel them. It's a problem for everyone regardless of what kind of ethnic cuisine they cook, but it's especially hard on Vietnamese people.
By now every house should have an external vent in the kitchen, not recirculating, and I'll explain why it has an impact on them. In Vietnam they cook dried salted fish outside because it stinks really bad, and American track houses don't come with an outdoor kitchen and so they have to cook it indoors. Most track kitchens have a recirculating vent hood that has a charcoal filter which won't help because the odor is too powerful. They need an external vent. The only alternative is to build an outdoor kitchen in the backyard which is expensive.
They enjoy communal cooking in large groups and so it's very common to have five or six cooks working in the kitchen at the same time. Therefore, they need much more space. Their work stations are larger, their walkways are wider, and they require more countertop space. For them, a second prep sink is an absolute must have. Also, it wouldn't hurt to have a 18 gauge stainless steel primary sink that has three bowls and an indestructible garbage disposal.
Cooking soup for a dozen people requires an industrial size pot. They're at least eighteen inches wide and at least a foot tall and so they require a lot of storage space. Also, huge pots like that call for installing a pot filler (a faucet) with an articulating arm behind the cooktop.
Sometimes they make a lot of side dishes and homemade sauces which means that they need more cooktop burners. I wouldn't hesitate to recommend a six burner cooktop. Depending on the circumstances they may need two separate cooktops in different locations.
They need at least three shelves that are two feet long to store their spices and tall bottles of sauces.
The refrigerator will have to accommodate an additional two full shelves of spices and sauces, plus three vegetable drawers, or at least two drawers plus a shelf for vegetables.
They don't use their oven. It's wasted space. They'll need one in order to sell the house someday and so I would recommend a base model.
They use their rice cooker everyday. Place it far away from the walls because it produces heavy steam which will eventually penetrate the sheetrock and cause dry rot in the wooden studs. Also, keep it away from the upper cabinets because the steam may eventually damage the varnish and warp the doors.
They cook in a wok almost every day. Woks are enormous and they require a lot of storage space in a base cabinet. They're also heavy.
They have several enormous, very heavy chopping knives which won't fit into a standard drawer or a countertop knife block. Those knives require special hardware on the wall, far from the ground where the kids can't reach them.
They have crab dinner parties where a large group of people sit together around the breakfast bar that's covered with wax paper, or on a huge bamboo mat, and they chow down on crab. Therefore, I would recommend creating a storage area for a commercial size roll of wax paper, which is sometimes called a "butcher paper roll."
Anytime there are a dozen people in a room they'll need cross ventilation in order to prevent a carbon dioxide problem and also sound absorbers such as cork wall tile to control indoor noise pollution. Additionally, anytime a dozen people leave their shoes at the front door it will create a major trip and fall hazard. They need a shoe rack. They may already have one for daily use but it's necessary to have a second one for their guests.