The difference between installation for sqlite and postgres is the difference between typing `apt install sqlite3` and `apt install postgres`.
The actual learning curve for sqlite is more complex because picking random sql queries on the internet will end in misunderstanding in underlying types in sqlite and broken data. Postgres tools ecosystem is much more expressive, because more people think about Postgres as about "real" database.
I'd go further and just point out the obvious - all DBs have incredibly well supported container run options in 2023, that mean you don't have to install the DB at all. I know of no DB that cannot be easily learned or deployed this way - even Microsoft SQLServer has a Linux image these days.
Since the advent of containers for running software, deploying any DB software is largely as easy as any other with a one line run statement, and if container image is cached you are getting a new DB in seconds.
If just starting out, running PG from a container is exactly how I would tell someone to learn today, and the process is largely identical whether they learn on windows, linux or a mac.
I haven't natively installed a DB since probably 2015 for any kind of local development use, its just a waste of your time more often than not now.
Yeah docker is great and I've done the exact same as you for a few years. But, I don't think I even knew what a docker container was until 2018, and again, as an intern or college kid with a school/work windows workstation telling them to run it in a container is a non starter.
Ever try to install postgres on windows? On a school or work computer you may or may not have admin access on? That's the kind of enviroment a lot of people (including myself) started in. In that sort of enviroment, it's easier to run sqlite3.exe database.db. And that's the kind of enviroment a lot of people (myself included) got started in databases.
If you have no experience with databases and are just starting out programming, PG is going to steepen the learning curve substantially.