You can reduce the number of charts on a tab to 10. The video shows you how to do this. Or should we add a minimum of 5 charts on 1 tab in the settings?
5 to 10 as a default option from your platform, if users don't customize their settings, is good. I would like to avoid scrolling the screen down and down, then miss important information, chats on top of the page.
The Bitcoin chart in 1st place (always) is a great idea! This can be a separate setting. If the user enables it, then the first chart will remain BTC/USD in any sorting.
The idea to pin Bitcoin chart on top of each page, is explained above. It's good that you like this idea and by this default pinned chart, you unofficial educate your users about importance of Bitcoin in cryptocurrency market. Your team proactively help them in investment and trading too through this pinned signal.
You can simply pin the Bitcoin chart on top of each page but you can do one more helpful thing like a short message like "This chart is pinned because of Bitcoin dominance in this market. You can customize, unpin it but we don't recommend you to unpin."