As ExtVariables becomes more complex, it seems useful to split in mutliple classes, for example for Hooks, the actual parser functions and so on. rECIT and rEPFN could be helpful as an example how to do this. This might especially be helpful for more advanced open feature requests.
While doing this, we could also do some breaking changes to get more standard file and function names. If some feature requests like T191575 are implemented on the way, it should justify bumping the version number to 3.0.