How can I add a font that is not listed?

Brand fonts can be added to the theme as custom fonts

The theme accesses the Google Fonts library (browse available fonts) by default.

If you are using Adobe Fonts (formerly Typekit), another online font service, or if you have licensed font files, these can be added to your child theme to override the theme settings.

You'll need to know the location of your fonts (either the font library URL or the font file URL from HubSpot files for each font) and which font will be the base font and which will be the accent font.

Follow the steps here to configure custom fonts for your theme.