Apple - Which font extension is used on both PC and Mac?

Mac OS X recognizes TrueType and OpenType fonts (.ttf and .otf) but not the PC bitmap fonts (.fon).

So depending on the copyrights of the fonts you may transfer the .ttf and .otf font files.

To install the fonts:

• Under Mac OS X 10.3 or above (including the FontBook) Double-click the font file > "Install font" button at the bottom of the preview.

• Under any version of Mac OS X: Put the files into /Library/Fonts (for all users), or into /Users/Your_username/Library/Fonts (for you only).

Though this is an old thread which I found while searching, here's an improved answer from Apple's official site: How to install and remove fonts on your Mac

macOS supports TrueType (.ttf), Variable TrueType (.ttf), TrueType Collection (.ttc), OpenType (.otf), and OpenType Collection (.ttc) fonts. macOS Mojave adds support for OpenType-SVG fonts.

So as per my experience, you can copy required font file (of supported format) into Mac and install it. I copied a font from Windows machine and installed it in Mac as well as Linux. It works well.

Another reference regarding the kinds of fonts which can and cannot be used in MacOS can be found here.