You edit and upload at the same framerate you record. If the raw files are constant 30fps the only good upload is constant 30fps. If your hardware isn't good enough to record constant 60fps then doing constant 30fps is better idea instead of using any non-standard framerates such as 40 or 35.
Variable framerate is so poorly supported by consumer software that it's almost always the wrong answer to any question. VFR is only good for streaming video over low bandwidth if the encoder supports it (OBS for example does), not for archiving purposes such as youtube.
Here's google's own guide for making HD video for youtube
https://support.google.com/youtube/answer/1722171?hl=en