I’ve had a collection of figures and vehicles for China that I put together for Crossfire many years ago. More recently I’ve based them individually for rules like Chain of Command, there’s not a lot to choose from when it comes to this theatre in 20mm, so there’s a mix of existing and converted figures and kits. There’s a longer post with more pictures on the blog here http://thetacticalpainter.blogspot.com/2022/03/second-world-war-chinese-national-army.html
One of the very few ranges of figures include a very small group from Wargames Foundry:
Otherwise it’s been a matter of adapting and converting existing sets like this HaT 7.7cm Feldkanone:
The Chinese bought tanks from a number of countries, so there’s a nice selection of light tanks from the interwar years to include:
The Tactical Painter - painting miniature armies for battles on the table top.