I decided to switch the main WordPress site from the Google Cloud back to (a different) hosting provider. Turns out a tiny Compute Engine costs at least 6 times as much to maintain and is actually way slower than just dedicated hosting despite my best efforts optimize every aspect of the software. For really small sites like this I guess it isn’t really worth the extra effort needed to maintain a dedicated VM.
I also used this opportunity to give the page a visual overhaul. The page is much faster and cleaner now in every respect.