As @candyman337@sh.itjust.works said, use a recruiter/agency. Post your CV to indeed and reed. It depends also where you are, in EU the job boards are different than US I guess. Speaking of LinkedIn, have you posted a message saying "hello world, I'm open to work and I've experience at this $stuff", and then ask your friends to share it. I got a couple of contacts that way.

Also, look for a resume builder/parser. Quick search gave me https://www.open-resume.com/ https://noted.lol/open-resume/

Pretty much everyone uses a CV parser when you apply, so if your is not formatted properly it's properly one of the reasons you get rejected. Another reason is that probably they recognize you are above what they need, so they know that a) you'd be expensive and b) probably get bored fast and leave. Put stuff you have experience with, specifying what your experience is, what your contributions were to the project etc. Saying "5 years of experience on $language" is not very meaningful. Writing "I created a Perl program to import data from Word docs to a MySQL DB, optimizing the code to use no explicit variables" (true story btw) is better. Or most likely "worked on $project for $industry, implementing $modules and enforcing $best_practice, collaborating with the wider team and helping mentoring other junior developers". Don't forget to mention non-technical skills. Companies look for someone whom is nice to work with more than someone who knows everything. A guru that alienates people is less worthy than someone that maybe don't know everything (and admits it) but can talk to others.

Re: time wasters. Holy shit 8 round of interviews! Even MS and AWS are less than that! MS was the biggest in my experience with 5 (but tbh it was all in a day, so not a horrible drawn out process, just different people). But you can ask at the beginning when speaking with the hiring manager what's the process, and you can decide if it's something you want to spend time on or nah.

Best of luck and don't be discouraged! I had a 3 months dry spell once, applying every day to multiple roles and being rejected. It's part of the game I'm afraid. Venting helps. Not getting a job immediately is not a failure in your part.

Best of luck!