An "in-view" pixel can tell you wether the your pixel was displayed on the screen. The "in-view supported" ensures the quality of the "in-view" pixel. Therefore, it can be argued that the "in-view supported" pixel is an ad on, which is more of an "nice to have" than "need to have".
You will be able to measure “in-view“ and "in-view supported" if the device where the campaign is being displayed uses an up-to-date browser. This is because the two pixels require the ability to support HTML5. Older browsers, such as very old versions of Internet Explorer, will not be able to support HTML5, and the “in-view“ and "in-view supported" will therefore not be fired.