How do I make Google photos my default photos app on Samsung S8

It's most apps including tapatalk.
Either way I am very active in Facebook groups and it happens to be a feature I use very often.

Between that and no system ui tuner I'm thinking I should go for a pixel or pixel 2 when it comes out.

Sorry for the delay on this post, but yesterday being Father's day I wasn't available for Forums most of the day. I just remember an option that you may try in the meantime.

I know it's not a permanent solution but you can always use Facebook Mobile version on a browser and you will have MOST of the App's features and sometimes, for the majority of people, that will be enough. I know that at least on this matter, by using the facebook mobile version it will allow you to select your Gallery Folders and you can even select the "Documents" option when it asks and there you can even select Google Photos, Drive, Dropbox or any other Cloud service that you may have already linked on the My Files app.
 
Yup you're both right. Instagram does it right. It is a Facebook issue.

Doesn't change my mindset on leaning towards a good native phone. Mobile Facebook would work but it would be a huge pain.