In my PhD I put some work on biorXiv that I never bothered to put through peer review and was pleasantly surprised to see it cited by a peer-reviewed journal article.
If you're a member of a recognized academic institution (as determined by email address I think?) then you can skip the endorsement step.
The thing that surprised me the most was that people watch what gets posted on arXiv, so they someone will probably read your paper if its an active research area, you may even find people discussing your paper on Twitter without ever promoting it.
If you have any institutional affiliation (eg even big tech companies qualify), you can post to arXiv. And it should be pretty easy to get someone to endorse your posting if you don't, it's basically to stop total nonsense getting submitted.