You can quite easily create a "Do It Yourself" OGN tracker from commonly available (and cheap) parts. What this DYI tracker will have "on board" is only limited by your budget time you want to spent and your imagination. Think whether or not you need a barometric pressure sensor, accelerometers, sd card port. igc logging, etc..) in your tracker(s).
Once you build your hardware you just install dyi-tracker firmware on it - and you're ready to go.
If you don't like too much soldering and want to build your tracker as quickly as possible, consider DYI OGN Tracker based on ESP-32. That seems to be an easiest options today. If you like playing with soldering iron a bit more (and want to spend even less) consider STM32 OGN DYI Tracker.