JSAUX has a transparent backplate for the Steam Deck, which also comes with taller back buttons and a slightly extended heatsink.
See inside your Steam Deck with JSAUX's $30 transparent backplate - The Verge
Transparent Back Plate for Steam Deck RGB & Vents
Your Asus ROG Ally could be transparent with Jsaux's RGB backplate - The Verge
Hardware Review: JSAUX's Colored Transparent Backplates for Steam Deck - Hackinformer
My favorite new Steam Deck mod is JSAUX's $30 see-through heatsink backplate - The Verge
JSAUX Transparent Back Plate Compatible for Steam Deck, DIY Clear Edition Replacement Shell Case Compatible with Steam Deck, Buttons with Three Different Heights and Feel - PC0106 [Crystal] : Video Games
Transparent Back Plate for Steam Deck
JSAUX will be doing more colours for their Steam Deck backplate
Transparent Back Plate for Steam Deck
On the fence about the transparent backplate from JSAUX, annoyed that they apparently don't allow you to use any promo codes. Both codes I've tried were provided BY JSAUX after providing them
JSAUX RGB Back Plate Review
JSAUX Transparent Back Plate Compatible for Steam Deck, DIY Clear Edition Replacement Shell Case Compatible with Steam Deck, Buttons with Three Different Heights and Feel - PC0106 [Purple] : Video Games