What is a small nodule by the tip of the first joint on the finger?

Finger cyst. That can be a small cyst either along the tendon sheath, a tendon sheath cyst, or one that originates from the joint itself, a ganglion cyst.
Possibly mucous cyst. This could be a mucous cyst or ganglion of joint. They develop in association with arthritis, which may not be symptomatic. Grooving of the nail plate can result from pressure on the nail bed. Since the cyst communicates with the joint, if infected, the joint can get infected too. Therefore, popping the cyst is not recommend. If the cyst pops or looks like it might pop, see a hand surgeon.