That's the right solution. But it won't work for other browsers because unlike Safari, Chrome of Firefox might be used on tens of different OSes and there is no need for marketing companies to know what OS are you using.
The pref names and their possible values:
# Visibility level of font families available to CSS font-matching:
# 1 - only base system fonts
# 2 - also fonts from optional language packs
# 3 - also user-installed fonts
layout.css.font-visibility.standard
layout.css.font-visibility.trackingprotection
layout.css.font-visibility.resistFingerprinting
Here's the Firefox bug about enabling these prefs, probably in Tracking Protection Strict mode to start: https://bugzilla.mozilla.org/show_bug.cgi?id=1736005
Switched all settings to 1.