The basic idea for the freewheeling chainring comes from tandem bikes, where one person should be able to pedal, while the second one doesn't do anything. I have never ridden a tandem bike, but this is where I got the idea.

There is also another detail, that you need to know, in order to understand how it all works.

Trial bikes (not trail bikes) usually have a special kind of drivetrain, where the freewheel is mounted on the crank and not the rear wheel. This allows for a very small rear wheel sprocket and extremely high gear ratios.

So to make this work, I used a trial bike crank [1] on which I'm mounting a special purpose freewheel [2]. The chainrings are mounted to the freewheel using this adapter [3].

[1] https://sickbikeparts.com/cranks-freewheel-isis-crank-set/

[2] https://sickbikeparts.com/front-freewheel-heavy-duty/

[3] https://sickbikeparts.com/freewheel-spider-4-arm-104-mm/