Another take on this: what would you try to achieve?
If you would just want to make your accordion heard wirelessly, you could likely use a pair of wireless audio adapters (the guitar things with a 1/4" TS jack). Or two pairs for stereo. - I'm having my FR-1xb at hand to try this, but I've just received another toy. ;-)
UPDATE: Yes, this works: apparently no impendance issues. - However, such a "dongle" on the bottom side of an accordion sits in an unsafe and uncomfortable position, notably when you're seated while playing. Using a short extension cable (or two for stereo...) would allow one to mobe it to a safer position. - The wireless adapters I used are (among) the cheapest on AliExpress. They may come under different brands, but their type is "A8". These are among the many devices using the 2.4GHz frequencies, so you could have a Plan B to purchase far more expensive adapters that use the 5GHz band. - If I'm not mistaken, the Receivers of these "A8" adapters can be set to merge signals several matching Transmitters (set to transmit on the same of four "channels"), and several Receivers can be set to one Transmitter (like one on a PA-system and on a monitor). Just remember to switch the Transmitters on before the Receivers.