Hi, I just found this post today and this is really informative, and I appreciate it!
I am also maintaining my soft fork on https://green.leafwind.tw
The purpose is to serve Traditional Chinese (mainly Taiwan) as a local community, so I removed all the fat language files and replaced the default feeds for more suitable recommendation.
Another goal is to maintain a minimum fork so that the App view can be more faster and less security issue, so I am also learning on how to disable features, but after weeks of struggling, I realized that it’s not trivial, either removing codes for iOS and Android, or removing a single feature can leads to a lot dependency issues to resolve. 
Looking at this post, there are a variety of different changes but seems no one is applying a systematical way on modularizing these features.
I am wondering if anyone can point me to some relevant forks, or relevant threads so that I can dig more? 