I think the boards that most meet your criteria and are currently available for purchase are below. Others can share more about the user experience for each but there is a link to each of the products for details.
Check requirements for a mobile device for each.
DGT Pegasus ($270)
DGT Centaur ($345)
SquareOff Pro ($279)
Chessnut Air ($225)
ChessUp (Note: there is a crowdfunding campaign for ChessUp2 with an estimated retail of $299 but not idea when it's going to be available... I wouldn't rely on the estimated delivery date in the crowdfunding campaign).
Apologies for the repetitive inquiry, but I'm seeking guidance amidst the multitude of options available. I'm considering gifting an electronic chess set to a child with a skill level of 1400+ Elo. My budget is around 250EUR/270USD. Ensuring a flawless experience is crucial as I've heard about potential bugs in some electronic boards. Could anyone recommend a reliable electronic chessboard within this price range to avoid any embarrassment during the gifting process?