I do like that it exists, but the change from 16:10 to 16:9 is a hard no for me. Probably the only off the shelf option for a screen to mash into the device though. Plus, the cost of it is nearly half the cost of just getting a refurb OLED deck, can sell the LCD one and get a new one for roughly the same overall cost as upgrading without all the downsides.
DeckSight: OLED mod for the LCD Steam Deck (www.crowdsupply.com)
Pretty nice but unfortunately no shipment to EU :(