I concur with some of the commenters that this read as a bit of a brain dump. It has a thread connecting several loosely-related topics.

Observation #1: You can also solve the tech stack problem with Heroku. I think the author's stack probably has a steeper learning curve, but is a cheaper option. I think it's a bit of an odd comparison (I won't say straw-man, as I don't doubt some people do this) to go from a fully-controlled simple setup to using AWS with a pile of extra crap. You can also, for example, run something similar to what he or she is describing on AWS, Heroku etc. (I.e. without the things in the AWS diagram he indicated like kubernetes and load balancers.)

Observation #2: I have not found WAL mode is an antidote to SQLite locks during multiple concurrent writes. (This is anecdotal)

I think regarding Go vs Python/Ruby etc. I completely get that. I would now like to check out Go on web. I use Rust for most of my software writing, but am still on Python for web servers, because there is nothing I can use for Rust that is as powerful and easy as Django.