Is it possible to re-order the channels within Teams so that you can choose which channel to have first, e.g. with the most frequent traffic or highest relevance, rather than alphabetical order?
Going one step further can channels with high traffic automatically feature first?
Yes , its vital this feature is added for proper funtionality of Teams
The workarounds by adding / changing the numbers in front of a Channel name as priorities shift is a nightmare as it doesn't change the SharePoint names / folders and anything else that's in the background of it.
Bob Sherman commented
Almost nothing in business is organized alphabetically, so this functionality is critical to allowing users to organize channels in a way that is meaningful/helpful to the consumers of channel info.