I just updated my macOS Big Sure Developer Beta to version 6. It all works just fine still retaining snappy response times for all things. After the installation I noticed the icons for hard drives had changed. Maybe this had occurred in a previous Beta, but I just noticed it today. Here is what the hard drive icons look like in Big Sur.
Hard Drive Icons
As previously mentioned, the Big Sur interface has been iOSified. That has bled over onto the hard drive icons. Here is what hard drives look like in Big Sur:

The External hard drive icons have changed to a more rounded 3D look. The Internal hard drive icon has a more detailed look as well. Here is another example:

The new rounded look is very noticeable. I really like it.
Conclusion
This is no great epiphany. I just wanted to mention it as part of the new look and feel of macOS Big Sur.
So, the new hires at Apple have made us slaves to their own personal choice of uniform Ugly Yellow icons for Hard Drives. Gone are the days of distinctive visual-hint icon images for individual external hard drives. (I’ve tried hard to change them. No luck!) External Hard Drives must now all look exactly the same. Can’t be changed! It’s the now law. Makes things easy for lazy Apple Engineers, screws us Users. I’m already getting data lost by file mis-placement on the wrong drive. One less reason to go Macintosh these days. Booo!
Until you mentioned that I never gave it any thought. But you are right! You cannot change the icon on a Hard Drive. Apple just keeps leaving us with less and less choices. Not good!