We may install as many as you wish and please keep in mind that one task request limit is to only 4 files (eot/ttf/otf) including the versions (Light, Normal, Bold, Italic) maximum at the time. Or if the font it's included also in Google Fonts then one task request is limited to just one font family.
Eg. OpenSansLight.ttf, OpenSansNormal.ttf, OpenSanBold.ttf,OpenSanItalic.ttf
The fonts can be selected for the whole store or just for a section/part in "theme customize. Also, we can hard-code it for you if you would prefer this.
Why is this? Because we need to convert the files to different formats (eot/svg/ttf/woff2) in order to support the majority of web browsers. This adds extra time for implementation so depending on the number of the files we may have to split your request into several tasks.
Also, please note that a lot of different font files on your store may lead to poor web design and a slower loading time of your store.