Automatic air vents in attic to replace plumbing roof vent

I put one on a garage sink sewer line (probably a bit too far from the sink)... It works.

However, like everything these days there is a law (code) about this stuff:

https://www.carsondunlop.com/training/resources/waste-plumbing-air-admittance-valves-and-automatic-air-vents-part-one/
https://www.carsondunlop.com/training/resources/waste-plumbing-air-admittance-valves-and-automatic-air-vents-part-two/

One typical issue with venting are kitchen islands with sinks. Obviously you don't want a vent stack going up from your island to the ceiling.

https://www.familyhandyman.com/kitchen/how-to-plumb-an-island-sink/
https://www.finehomebuilding.com/2019/09/10/a-new-old-way-to-vent-a-kitchen-island

My in-laws have a "island" like sink and no direct vent stack (inverted U system). It works OK, but after decades (sink with garbage disposal/etc.), sludge and slime did build up in the piping (brother-in-law had to replace the piping when leaks started--just followed the existing design--and I had to snake out the system at times (sewer continues to a wet bar sink 20 feet away).

-Bill