I'm 24 years old now and have been working as a developer for about 5 years. I've never finished my degree, and I always felt that I'm missing something in my career because of that. I've decided to go and get a one from The Open University which contains Math, Stats, Algorithms, and some Data Science modules. I have always been interested in cryptography and NLP, and tried to learn something on my own, but never make it, because of the "hard math". Also, trying to learn math on my own by MOOCS and books also didn't bring any results.
And now I'm wondering, is this commitment really worth it? It will take ~6 years and $25k to complete it. Can I benefit from it in the future, or it would be better to try approach self-study again?
Are you able to take the credits you have and complete a bachelor's in something like business administration from a local university/community college?
If you believe the quality of education to be better, it might be worth considering. However, I'd caution that the only benefit you'd be getting would be access to a professor. At the college level, a well-written textbook is just as valuable as the average professor if you're not using office hours. If your intention is to get help from someone in specific subject areas, I would recommend just hiring a tutor. You'll save a lot of money and can get actual personalized help on whatever specific issues you have.
In terms of opening doors, I doubt it moves the needle that much. At this point in your career, a college degree has almost no value unless it's an upper level one (like a masters or a doctorate). Every person I've talked to has indicated that their undergraduate degree stopped mattering once they entered the workforce and had legitimate work experience. If the Open University is only offering you an undergraduate degree, I can't imagine that would do anything for you even if the employer trusted the school.
Others have mentioned it, I echo their thoughts. I did an online MBA and if you have difficulty with MOOCs, it's not going to be easier with an online degree. MOOCs are cheaper, especially if you are not looking for an official qualification, in which case you can simply audit the courses.
You don't say where you are from in Eastern Europe, but mathematics is universal and mathematics has historically been a very strong subject in the east. Banach and Tarski were Polish; Shor was born in Kiev; and many others. So, if online isn't for you, I would not hesitate to study mathematics in your own country. You will find the access to like-minded students valuable and your own online skills will let you research topics that interest you.