There were no apps for v3 but the modules, plugins and themes and languages should all be at each developer's site. Several developers listed their stuff and still do at my scripttechs.com, including my own scripttechs products.
v3.9 has been end of life for months. It is not supported here. It is supported at ScriptTechs through support there if needed. For add ons, each developer has their own terms for what they support. I still support my scripttechs add ons I made. You would need to check with each dev.