I can chime in about this....heck, I could write many pages on this subject. I started learning to sing as an adult (40ish). No prior training, no skill, no natural ability, etc. I really started from zero. I've spent a lot of time and effort with different books, methods, teachers. It's been a long, slow, often frustrating process, but I enjoy the journey and value whatever progress I make.
As far as resources, I find most of it frustrating. Many resources seem to assume a certain level that I wasn't at, or they follow a blueprint that focuses on things that have no relationship to my weaknesses and needs. (Kind of like a guitar "method" that shows you pentatonic scale diagrams and says "Eric Clapton uses these scales") For this reason, if your budget allows it, I recommend some in person lessons with a good teacher. The trick is to try teachers until someone clicks with you. This is hard to do. I took several group classes and private lessons with different teachers, and most of them didn't really help me. In retrospect, some hurt my progress.
A good teacher should zero in quickly and be able to articulate what you are missing, not just apply chapter one of some book without regard to you. As an example, many teachers I had focused on all sorts of breathing exercises. When I started with the teacher that really helped me, on the first day she said, "nah, you can breathe fine, you're dropping the soft palate and pulling your tongue back". And then two years of tons of different exercises and songs followed, with the exercises changing constantly as I got one part working and broke something else.
Vocal instructors are expensive (think $100/hour), but if you can find a good one, even a few lesson will be super helpful.
That said, I found some materials from Susan Anders helpful:
https://susananders.com/home
And the great teacher I had is here:
https://tricialeines.com/
(As an aside, once I started working hard on singing, my guitar playing improved a lot. Singing is the ultimate ear training.)
Cheers!