Throwing things here and looking into them. Will do an official write up later.
Goal: Lower power consumption
https://www.amazon.ca/SoundOriginal-Universal-Motorcycle-Electric-Waterproof/dp/B072QBNTSM/
12V, 1.5A, 105dB
https://www.amazon.ca/Speaker-Waterproof-Electric-Motorcycle-Scooter/dp/B07GH7HNDC
12V, 3.5A, 115dB
This horn was ordered for testing, as it was both UNECE Reg 28, low (ish) power consumption (4.5A vs the 9A of the old horn): https://www.amazon.ca/gp/product/B000DINKPQ/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1