It’s just a power cable. If you’re willing to give up the warranty, there’s no reason that you can’t graft the ‘special’ end to a cable of the length you want. In my past I’ve used several ‘extensions’ from Flexson to  create shorter cables, since I wanted to keep the originals pristine. Just had to get extra wall plugs to attach at where I cut the cord. 

@Airgetlam , thanks for the suggestion. I am mildly uncomfortable to do grafting and run that cable along a wall. I am hoping there are third party power cables that are compatible with Era 100 or better sonos come out with one. 

There likely are, if you do a Google search, or an Amazon search. They’re unlikely to match exactly what you need, in my experience, but no harm in looking. I know Flexson has/had some, but I think other companies are out there, too. Vebner, for instance, doing a quick search on Amazon. 

Several options here, as long as you can get from the Sonos to an out-of-sight location you should be able to hide the cord connector if there isn’t one long enough here:

https://www.amazon.com/s?k=sonios+era+100+power+cord&crid=38RMQ7YYNCLP5&sprefix=sonios+era+100+power+cord%2Caps%2C145&ref=nb_sb_noss_2

Another option is a very short power cord and an empty wall box with a cable access cover that the connector can be hidden in. Then use a low visibility cord from the box to your power outlet.

https://www.amazon.com/Bates-Choice-single-brush-plate/dp/B09WJCFT1F/ref=sr_1_21