I putt with a relatively short putter (33") that I also have bent upright a few degrees. My arms hang straight down. Right forearm 'slap' motion back and through, like tossing a ball underhand.
Yep, the easiest way to putt IMO.
Like you have a racquet in your right hand. A bent right wrist 'slap', kind of a heel punch at 'underhand toss' tempo. Racquet face angled slightly forward (grip leads)
Hands slightly ahead. Angled hinge action, no roll feel.