It can be difficult to differentiate between various symptoms to ascertain the cause of lumps, stiffness, pain etc in the hands? Some symptoms are more clear cut than others, trigger finger and carpal tunnel for example.

A protruding tendon, if that's what it is, could be a pulley injury, inflamed sheath, or sign of a DD cord. Cords are often mistaken by the lay person for tendons and usually follow the same lines, but there's a clear difference in feel between a developed cord and a tendon. I would expect an experienced hand doc to be able to differentiate. Are there other symptoms, usually nodules, pits that indicate DD.

Now let's say it is DD and other symptoms develop, and the tendon does indeed harden and turn out to be a cord. The basic evidence based treatment options are RT in the early stages before contracture, then NA, Xiaflex and surgery to straighten contracture. Without health insurance in the US, I don't know how it works to seek one of those treatments. Perhaps look into that.

I also think I've said this before, if it's not functionally bothering you, not painful, then "wait and see" but keep a record with photos, maybe monthly, and just carry on.