LineageOS is based on the Android Open Source Project with extra contributions from many people within the Android community. It can be used without any need to have any Google application installed.
All the source code for LineageOS is available in the LineageOS Github repo.
Here is the first Android 10 for Serranovelte GT-I9195I. Of course everything is still pretty much at the beginning ( There aren't even official gapps yet ).
There could be mistakes here and there.
E.g. battery display in percent does not work. Lack of translation in other languages. Possibly other things too.
But a lot of things are already working quite well.
1. Download the zip(s)
2. Install a compatible Recovery (TWRP 3.2.x or higher is recommended)
3. Perform a backup of your current ROM (Optional)
4. Make a full wipe (system, data, cache, dalvik)
5. Flash LineageOS
6. Optional: Install the Google Apps (search for BiTGApps-arm-10.0.0-)
Download: LineageOS 17.0
[ROM][10.0][UNOFFICIAL]LineageOS 17.0 [SERRANOVELTE GT-I9195I], ROM for the Samsung Galaxy S4 Mini
ROM OS Version: Android 10
ROM Kernel: Linux 3.10.x
Beta Release Date: 2019-12-08
Last Updated 2019-12-09