I suppose the first question would be, whereabouts in the world are you geographically located (country/state or equivalent).
Second question, how far are are you willing to relocate?
> I'm a mechanical engineer and wanted change my career path. I have some experience with embedded systems at university but it is very limited
Does this mean you've been to university and have a degree in something?
While you can't do anything about the "software engineering degree" in the short term, you could work on the "experience".
To that end, look around
Topics on GitHub * GitHub
Best Open Source Windows Software 2022
Find a few you like the look of, and lurk on whatever developer forums / lists / channels are available for a week or two, so you can gauge the personality of the group.
Pick things which are active, not something where the last commit was months or years ago.
Read whatever code / documentation / bug trackers they have.
Pick one you're comfortable with.
Introduce yourself briefly, outline your skill set, ask if there is something you could work on.
You'll gain experience in
- working in a s/w team
- having code reviewed (and maybe reviewing code of others)
- source control systems
- continuous test / integration systems
- reading and writing bugs
- analysing problems
- and so on.
These are all necessary soft skills to have, which have nothing to do with knowing where the curly braces go in a C program.
After a few months, it should be something you could put on your CV.
For no other reason, it would demonstrate that you're a proactive person.
Good luck with the search and project.