Is any music written on any scale other than the octatonic one?

Sure. Debussy used a whole tone structure in a lot of his music without any half tones.

Yes, Chinese music uses a pentatonic scale:

https://en.wikipedia.org/wiki/Chinese_musicology#:~:text=and%20A%2Dflat.-,Scale%20and%20tonality,zh%C7%90%20%E5%BE%B5%20and%20y%C7%94%20%E7%BE%BD.

Indian music Ravi Shankar “The “raga” is the melodic form, but it is not just a scale, Shankar says. There are roughly 72 parent scales. And each scale has hundreds of ragas, which can be pentatonic (five notes), hexatonic (six notes) or full scale (seven notes).”

Being an Indian, I grew up learning and listening to scale based music. Indian classical music is broadly divided into 2 systems – Carnatic and Hindustani. Carnatic music is ancient and has been around forever….I guess. The Hindustani version (of which Ravi Shankar, mentioned in the other answer here, is famous for), was created in the medieval times and has some influence from the middle east. Both these systems play around with scales and arrangement of notes within the scales. There are 72 parent ragas (as mentioned in the other answer) and they are called Melakarta Ragas. There are thousands and thousands of derivative ragas (derived from the parents), of which, around 400 or 500 are famous (they are more pleasing on the ear than the rest). If you are a music lover and do have a little spare time, I urge you to read about Carnatic (or even Hindustani) music. It would open up a treasure trove of structured information for you, as Carnatic music is one of the most structured music systems in the world. In fact, many western musicians (not necessarily classical) have started experimenting with Indian music.

Not that I know of.

I was going to mention the Indian ragas. I have no more than a passing familiarity with them. @AK‘s response is a Great Answer.

The pentatonic scale is found in many cultures, in many variations.