I need to change technology to avoid burn-out. 7 years in messy mobile world is more than enough. It feels like all my effort to get M.Sc, solving complex math & CS problems, everything was for nothing - in the end I write apps that display list of elements on the screen. Moreover demand on Android developers in my city is decreasing, right now there is no offers at all.

I think natural candidate for my next core tech is backend Java. I have about 7,5 years of commercial experience as an Android Developer and 3,5 years of experience in tutoring - I created Java, Kotlin and Android courses for one of the biggest IT companies in my country. I know Spring and Hibernate.

Now the funny part. I don't know how to change my job and I am scared. I am scared that recruiters will ignore my CV or I will fail on interviews due to lack of commercial experience in Spring/Hibernate or that I will get much smaller compensation than I have now - due to morgage I would like to avoid this if possible.

I want to write some project and publish it on GitHub just to show interviewers that I am skilled enough and I can use these tools. But I have no ideas. If I need to write code then I want to write something useful, not another "pet store" that solves no problems.

What are your recommendations?