We have confirmed that INON accessories usable/designed for GoPro HERO9/10 are usable for HERO11 as well.
Variety of INON adapters, tray, arms, tripod are ready to use via SD Front Mask for HERO9/M67 Filter Adapter for HERO9.
[Combination example of INON accessories and HERO11]

Center right: UFL-G140 SD semi-fisheye lens on HERO11
Right: UCL-G165 SD wide close-up lens on HERO11
Please refer below link page for detail of INON accessories for GoPro cameras.
http://www.inon.jp/products/gopro/hero/sdfrontmaskhero9.html