In my experience (automotive) the compressors put the H in Hefty. That being said these seem to work quite well:https://www.amazon.com/Bicycle-Bike-Horn-Bell-Adults/dp/B000ACAMJC/
Greatly recommend the large ones for automotive use: Ex: https://www.amazon.com/Viking-Horns-003A-Decibels-Compressor/dp/B07T32C4BW/
I strongly recommend getting an AirZound from Amazon. I’ve been using is for a few years now and it comes in handy. The only thing to be mindful when you’re using it to not to startle other cyclist on the road
If you want really loud, give this one a try. But be prepared for a lot of dirty looks if you use it on pedestrians or bicycle riders. Unfortunately it doesn’t have any volume control. It’s just always really loud.