That's smaller than "a few GB", so no problem ;)

SQLite can get tricky, if the database files get bigger. But up to a few GB there should be no problem at all (SQLite supports up to 281 TB though)

They start getting a lot bigger once you start accepting and saving user input, e.g. running a WooCommerce store.

The practical DB size limit for WordPress is around 60-70GB. After that it becomes rather sluggish.

That is terrifying that you know this. I am almost curious but would rather not know more.

It'll become unusable at a few hundred meg when it takes 180 SQL queries to render a landing page.. I wish I didn't know that either.

A few hundred megs for a single page? Yes.

For an affiliate site with millions of pages you need much more to make WordPress sluggish. On the other hand, it only takes a single badly written plugin to achieve the same effect. :D