Does the thumb technically count as a finger?

Yes!: I would argue its the most important finger. The opposable thumb was a critical evolutionary leap for humans!

Digit: The thumb counts as a digit but not a finger in the strict sense.

According to NLM: The national library of medicine (which is closely involved in the naming of scientific and medical terms) classifies "thumb" under the term "fingers" in its hierarchy. But it was important enough to give it its own term, where the other 4 digits were not. So i guess thats where it stands. And who am i to argue with the national library of medicine?

Thumb is first finge: Yes thumb is counted as a finger and, in medicine it is counted as first finger, and others are numbered accordingly.