The issue is not only one of funding, but also of publicity - GPL code is great, but not profitable. For widespread adoption of a software, it needs to get enough publicity. A very large number of people will never even have heard of any of the most used GPL-licensed pieces of software floating around.
Without publicity, projects get less attention, fewer developers, users, revenue, etc.
If your goal is to rewrite your python code in C with minimal hassle, start thinking of objects as structs with functions attached to them. If you detach the functions from the structs, instead having them take structs as an argument, then you can obtain something which is C-like but likely very unoptimised.
Personally, I think I would steer you towards Rust or C++ instead - both can run just as quickly, but have more OOP features and modern features which may make moving easier. Learning C is still a very good thing to do, but I’m not sure this project would be the best project to do that with.
I enjoy reading stories on RoyalRoad, and in general people who read web novels have a far greater patience for long stories than standard publishers would - The Wandering Inn has over 12 million words, and it’s not over yet. Mother of Learning, the top rated novel, has a word count of around 800,000.
That said, trying to trim down your book has a good chance of improving the story as a whole. One of the reasons why Mother of Learning is so highly rated is because every single detail that is mentioned always leads somewhere, and it all gets brought together nicely at the end. If you wanted to trim it down, I think that trying that approach would likely work better and probably improve the novel.
I think what you do depends on what kind of future you’re imagining for yourself as an author.
Adding on to the ones already named, A Practical Guide to Evil and Only Villains Do That are both very enjoyable. (There are a lot of shorter stories which I am very excited whenever they update, or longer stories which are not quite as good as the ones already named)