You should carefully check the license of each font on Google Fonts. They're not all under the same license. Yes, many of them are permissively licensed, but that doesn't mean you have the right to redistribute the ttf/otf file yourself as part of an application, since you need to comply with the terms of the license as it is written.

I've been meaning to roll my own font with https://github.com/glyphr-studio/Glyphr-Studio-2 but I've never gotten around to it. Then you can build on top of the public domain fonts or properly license fonts on Google Fonts.