re: 3D Model Resources
Thingiverse.com isn’t really a marketplace, in that all the models there are free. Some of the models are “teaser” models with more extensive selections available via Patreon.
Patreon.com - many 3D modellers have Patreon accounts set up which allow access to their library of models.
You could add MyMiniFactory.com, which includes both free and paid models.
TurboSquid free STL models
(For-pay models and other file formats available as well, including rigged models for animation - extensive library)
https://www.yeggi.com is a meta search engine for 3D models. Shows models from many other sites. Use “Search Options” to the right of the search box to limit searches to free models, if desired).
TinkerCAD.com shows models made by other users as well as an online tool for making your own. Note: does not play well with some AV software.
3DHubs.com is the Uber of 3d Printing - it is a clearinghouse where one can get their part printed by others. Some are professionals, some are hobbiests. Includes both additive (FDM, Resin, powder printing, SLS) and subtractive processes (e.g. milling).