Looking for code and app templates that people have shared online that we can build off of to adapt to our needs.
Great question! Reading through existing code is a great way to learn how things work.
Of course, it can also be beneficial to learn the basics starting from the ground up: e.g. following tutorials/documentation at https://developer.android.com/guide , or other "introductory android" tutorials.
I just found a good website with over 900 various free templates. Hope this helps someone else too!