Hori has just announced the Stereo Headset Hook for Nintendo Switch. This device will apparently let you mix voice chat and game sound from both your mobile phone (voice chat) and the Nintendo Switch (game sound).
Whilst this isn’t an official Nintendo product (although likely to be licensed), it does appear that this kind of splitting device will be the only way to get both voice chat and gameplay with one pair of headphones.
It’s going to launch on July 21st for 3480 YEN which is roughly $45.
Google translates the listing (which is currently in Japanese to the below)
“Stereo headoset Empera Hook HDP for Nintendo Switch” will be released simultaneously with Splatoon 2! With a headset that reproduces the gear in the game, you can mix game sound and voice chat and listen! (¥ 3480 excluding tax)
?2017?7?21????????????????? ???????HDP for Nintendo Switch??Splatoon2????????????????????????????????????????????????????????????(???3480) pic.twitter.com/q1T4Oy3Sr3
— HORI /?????????? (@HORI__OFFICIAL) June 1, 2017