That's a great goal to have, and if you are dedicated to learning and a lot of trial and error I believe you can do it!
Most of the times I've found mentors have been when I've been collaborating on a project with somebody smarter than me, or sharing what I'm doing in public and people give me tips and advice.
Some people will give criticism, and some people are very opinionated…so if you're sharing anything in public you need to grow a thick skin toward criticism, but by sharing openly it lets other people who would mentor you, find you and give you the information they know.
If iOS (Swift), Django (Python), and PostgreSQL are the stack you want to work with I could recommend doing any of these:
- creating a Github account if you don't already have one
- try following tutorials for your chosen stack, and create simple small projects to put online on Github or other places
- in places like Hashnode, Twitter, Slack, or any place developers have discussions, try seek out iOS developers, Django developers, and PostgreSQL developers and show them what you have built and ask how it can be improved
- if you do find some good communities online around your stack, you'll naturally learn a lot just from the discussion going around between others as well
- over time there may be contests, challenges, or maybe a reason why you would want to volunteer time to build something for a cause, or to build open source software. Projects like that (as well as paid work) are great chances for you to collaborate with better developers who can mentor you and bring you up to whatever skill level they have
Good luck on your journey toward full-stack!