It's required to have a related university degree to receive the Blue Card and my Masters doesn't match here obviously.
I know it wasn't your question, but let me challenge you on that one:
There is a really short questionaire one can fill out on the official government page to determine what the best way to work in Germany would be. Ironically, it is specifically for foreigners wanting to work here, but I could only find a German version. Go figure.
According to this, your university degree does not have to match your actual profession, if you make more than 55.200€ per year.
For MINT and medicine they even have an exception that it can go as low as 43.056€ as long as it's competetive locally (so they aren't exploiting you specifically, they are just not paying as much in that region of Germany).
As a software developer, 55K per year seems doable. Especially since COVID and remote work, companies are competing for developers in all of Germany, and cannot really get away with paying lower wages to people outside of Berlin or Munich, when those developers in formerly lower paying regions get offers from Berlin or Munich and don't even have to move there.
That is if you "just" want to develop software, any software. If you put your medical degree to good use and find a company that develops medical software, I'm sure your degree is a bonus that should come in handy both in getting the job and in getting better pay than people with "only" 6 years of developer experience.
So if you can find a company in Germany, preferably in a high-paying (but unfortunately also costly) area with a medical connection so they value your title and pay 55K and above, you should not have a problem and should not need any additional certifications.