itch.io

Yes, completely. If you're downloading to Android, use the APK file. It'll ask you to install. If you're downloading to Windows, you'll have to unzip, find the exe file, & it might give you a warning about coming from the internet, so select "More info", then "Run anyway".

If a game has lots of user activity and isn't recently added then it's safe. There are games which people steal then add malware and upload with another name, and it takes some time for it to get discovered and taken down. This is because anyone can upload games without them being checked first unlike steam, gog, etc. Also developers can delete comments and disable them altogether so people can't warn others if something is malware.