Yep, the larger and more prestigious conferences may be harder to break into (as they have so many people submitting) but there are smaller conferences that are probably desperately hoping for more people to submit proposals. Or they were before COVID. I'm not sure how the transition to all (or mostly) virtual has affected the conference scene, but that's the way it was in the past.

Based on my own experience, I'd say that you can always start out by speaking at local user groups or Meetups, build a resume of talks you've given, then apply to smaller / regional conferences, do a few of those, and ... well, that's where I stopped. All Things Open is the most prominent event I've presented at. But the point is, bootstrap and work your up the ladder.

Look at the whole thing holistically too: blogging, putting content on Youtube, open source projects, etc, all go towards building your overall image and presence "out there".

Most conferences will accept almost anything even tangentially related to their focus. Because nearly all proposals will come from companies trying to market their crap in conference talks disguised as something else, when they get applications from people with something really interesting to say which is not related to something they're making money on, they will almost certainly accept. It may b e hard for the first couple of talks as you don't have any experience doing it, which means you may suck at it, but you can start by talking at local meetups or even internally at your company, which is less challenging and will get you some experience to get started.

For example use https://www.cfpland.com/conferences/ to get a list of CFPs (invitations to submit a talk.)

I worked at Uber too. Turns out if you work at the right places, it opens doors for you. But yes most conferences have a "request for proposal" system.