BRIDE Co. shared this post on Instagram today about their seats on the new BRZ (and I imagine the GR86 as well). The BRZ seat rails are the same as the existing ZC6 seat rails which means "almost all seats can be attached."

(Translated from Japanese):

Subaru and new BRZ can also be exchanged for BRIDE seats!
The new BRZ is the same as the existing ZC6 seat rails (F901 ** / F902 **). Almost all seats can be attached.
* As of September 20, 2021, the passenger seat side seating sensor is not supported. Seat replacement on the passenger side is not compliant with security standards.

http://instagr.am/p/CUCZqqbNd21/
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