Interestingly, the Arsenal da Guerra do Rio de Janeiro produced some interesting items at least in the 1930s-50s period.
I found three products in the COnde de Linhares Military Museum in Rio, but there may be more of course!
In 1936 this prototype conversion of an older Krupp 75mm field gun was made.
Much along the lines of other conversions into box trail (HIH, Osaka, Rheinmetall, Turkey):

Who has more info on this?
The post-war a 120mm mortar was produced:
Also in the 50s Bofors 40mm L60 were produced under licence, at least over a hundred!
Any more info on the company is welcome!