Interesting read, but I find it very lacking. PGSQL memory consists of lots of parts; shared_buffers, work_mem, maintenance_work_men, OS Cache size, etc. For those who are interested in a deeper Postgresql tuning tutorial, I suggest this[1] as it highlights a number of important tuning options - specifically for PGSQL 17. Once your DB has been running for a while, run the postgresql-tuner app[2] to see if you have correctly applied RAM settings[2]. The repo has been around for a long time, but I find the recommendations (especially the estimated RAM usage) really good.
[1] https://www.pgedge.com/blog/postgresql-performance-tuning