The OP isn't looking for how to land a job, they are looking for how to actually become a better software engineer. People that are better at interviewing than they are at engineering are not doing anyone a favor.
It takes a lot of courage and insight for the OP to recognize their predicament and come to the solution of applying for a junior position.
I have over two decades professional experience across many organizations and I contend that is an absolute truth that one can spend years (even seven) with little to no mentoring and advance in skills less than an equally adept person who had one or two years on a team that really helped them grow. I've seen it happen and I've had it happen to me early on when I saw an engineer I used to mentor (but I had none myself at the time) leap frog me in capabilities when he went to another job that had even better mentors.
Getting better at interviewing is not going to help as much as getting a job at a company that gives them better support. If it takes a junior position to find that environment, so be it. But expect to advance extremely quickly, so set that expectation with the employer that they will support the promotions as they are earned.