This is what I know So far.
All of the pumps I have seen from suspension brands are just are branded of two brands: https://www.giyo.com.tw/ & http://www.beto.com.tw/products/index.php?index_tag_id=15 There different variations, different handles, different heads, colors, finishes, & they get customized to fit the brands. but there are differences, some can take more pressure than others.
Pumps each by Brands/Manufacture’s pumps next to each other
The Pump on hte left is a Giyo GS-02 rebranded for Marzocchi & on the right has no branding but comes with Trek Bikes & it’s a Beto SP-002AGN
pump to the right is made by BETO and is rebranded for: Marzocchi,Monitou,Spin Doctor, pump is a
fox use the same body but with round handle & Fox branding on inside the pressure meter
the pressure meter is also used by RavX and Syncros( now owned by Scott sports)
the screw-on valve tip is also used on Shockmate 2.0 Suspension Pump
with Marzocchi pump you loose less air(I mean fro mthe pump hose not the suspension of course) when unscrewing it from the suspension,and the air release button releases less air than the trek pump
Giyo makes pumps for Fox & Marzocchi, DVO,Rock Shox