I have been using Sena intercoms for many years now.. SMH5 - SMH5-FM and now a 10C.
Always wanted a handlebar remote... just one for basic functions.. But your units are no good for me
Big hands and short fingers mean anything clipped on the grip either impedes switchgear access or falls off and the earlier unit was just to far away to be useful.
I ride a bike with full handlebars, like most adventure/street fighter/naked bikes these days so...
Why don't you make a simple rectangular box, with two buttons on the front, one on the left hand side and two buttons on top.
The box could either be powered and fixed in place but maybe more people (me included) would prefer it quick release and rechargeable so it can be switched between vehicles (you can sell adaptor plates the same as Givi sell their rack fitting kits)
This would mount over the left hand switchgear via means of a mount that attaches to the handlebars just to the right of the switchgear - or - via the mirror mount - or - even an adaptor plate form the two screws/Allen bolts that clamp the switchgear together..
This "box" needs to be programmable so people can choose the button control they prefer... as no matter what you do someone will complain, say "can you add" or " why not this" (just like me :-) . Cannot be that hard to write software where the interface is just a list of options and you assign each button the same as you do a radio station??? (maybe with the on/of/volume button fixed as its the only one that need to rotate)
For me, on the 10C, an initial set up would be
Left hand front button (say 18mm) is the "press for 3 sec " (to avoid problems when adjusting volume) to turn the "box" on/off and rotate for volume, and has a single "bump" (maybe led lit) or a knurled outside edge - but it must be winter glove friendly.
Right hand front button (say 15mm) is "press to turn on/off camera - press 2 sec to start/stop record".
The side button would be to take a picture or hold for 2 sec for another function.
The right hand top button would be to change recording mode between continuous and "loop". This would need an led to identify, for me, continuous mode, again with the hold for a 2 sec for a second option
The left hand top button turns off/on music/ radio, again with the hold for a 2 sec to switch between (generally just let my music random play and don't skip)
I do not use a phone while riding and happy to keep the intercom system "as is" but having the unit programmable means however you want the main functions is how you set it...
And as you can guess not a fan of "one button does all" or a mini joystick when wearing thick gloves. Youngsters might like them but I am 62 and not so nimble.
You can add more buttons but a five multi action layout seems a good place to start as you can have your most used options on a single, quick, press and the less used ones on a long press,... and.. Really guys... how hard is it to write some software, these days, that allows a box to be connected to a computer, or phone, and the user can choose there own "favourite/must have" function.
For me, and the 10C.... It's something that is simple
You make it I will buy it