What's the best word to simulate an adjectival form of "camaraderie"?

It would be comradely:

(graded adjective & adjective [usu ADJ n])

• If you do something in a comradely way, you are being pleasant and friendly to other people. [formal]

• They worked in comradely silence.

Collins Dictionary

A simple and straightforward option would be friendly.

After their hard-won victory, John and Trent slung their arms around each other's shoulders in a friendly embrace.

M-W:

friendly adjective [friendlier; friendliest]

1 : of, relating to, or befitting a friend: as
a : showing kindly interest and goodwill
b : not hostile : a friendly merger offer; also : involving or coming from actions of one's own forces : friendly fire
c : cheerful, comforting : the friendly glow of the fire

His friendly smile was reassuring.
They maintained a friendly correspondence.