What's next?

I just reached the Top for the first time, 6,5h and 1666 Deaths on keyboard (did tear up). Its not my first attempt, but I didn't get this far on my old steam accounts. Now I didn't care about collecting any collectables on this run, and I dont know what to do now. I know there is still a part after the summit, but it requires those hearts.

I've seen that you can get a golden flag pole if you collect everything in one run, what exactly is meant by that, can I achieve that or should I play it through on my first profile first, I'd really like to get a run with all golden flags, is this realistic and how exactly can I do it, what is necessary and so on? What should I do next?