Odds are you do have something interesting to speak about. Many people are experts in very niche things and don't even realize it. You may be very proficient with a niche piece of software that is not well documented, or may have created software to solve a very specific problem. Writing blog posts about your niche knowledge can be tremendously helpful; I can't tell you how many times a single blog post about an obscure problem has saved me hours (possibly even days or weeks) of research when I've encountered the same problem.
And if someone doesn't find it useful, well, they'll just stop reading and go somewhere else.
I think it's useful to view your mind as a garden. If you plant nothing then all you'll grow is weeds. If you get rid of the weeds and plant interesting ideas by engaging with new ideas, then it will grow interesting ideas on its own.
TLDR version: publish TILs (Today I Learned) since then there's no pressure to say something new - just write about a thing you just figured out. And write about projects that you have done.
Ofc one can have his own pet projects and only blog about them. But in the world where a cat tiktok account was allegedly used for spying there is no such thing as private tech blogs anymore.
I blog when I feel like writing rather than when I have something to write about. Then I go to https://myactivity.google.com/myactivity?pli=1&product=19 and see what I was researching in the last month or two.
Theres usually something there where the existing articles were out of date (because tech!) or maybe it took me multiple results to actually solve my own issue.
That might be a way for you to find things.
Also I write for myself, I'm basically documenting for my future self so I dont have to research the same thing again. Some of my tech posts are just 2 lines of shell script and brief description so I can search google for my own content later but these posts still seem to be useful to other people based on views.
I think this could work for any blog where you're just writing about your interests or hobbies!