Ask HN: Want to change from front end to back end. Resources?

I'm currently working as a frontend engineer for a small agency (mostly using React and TypeScript). As much as I like the place, I want to grow my career towards backend, which is something they don't do.

For this reason, I want to learn backend in off-working hours. I'm willing to dive deeper into algorithms, data structures and maybe choose between Python and Go.

I read a similar question asked in another online community, but the response OP got was to "find a company willing to train them". I want to teach myself enough to be able to apply for backend jobs, and not to find a company willing to bet that I can learn backend on the job. Not only is my local market competitive (I'm junior) but it also lacks opportunities.

Are there books to read, blogs to follow, resources to digest, that will help me grow up to an acceptable level to be considered for a backend engineer position? They don't even have to be directly relevant with a specific stack or anything. For example, a recommendation I got from someone was to read "Designing Data-Intensive Applications".

You can also assume that I know how to Google, it's cleaning up the noise in the results which is time consuming and prone to errors, given that I don't know what I don't know.