Yes, I was and still am a Muslim hence the reason I didn't participate in worship. My parents are straight-edge Muslims. I think that while it wasn't ideal, they were comfortable enough to let me attend a school like that because there was a level of trust. If I was ever unsure, confused and conflicted about something they said or taught in school I would let them know. I studied it (albeit more extensively) the same way all the other kids studied Judaism and other world religions in other schools. My dad would often ask me what I specifically learned that day or week and tell me what is Islamically correct, where they went wrong and why it is/isn't that way. He himself used to 'study' Christian and Jewish scriptures to find out what the locals believe in. There was a guy that lived 3 doors down, he used be a member of the other (Catholic) church in our town until he withdrew to agnosticism. I don't know what the English word for it is. I think it was the equivalent of 'Brother' without the honorific title. Him and my dad always used to debate in our back yard in English (I barely understood it at the time). He used give my dad religious (also Jewish) reading material until one day he reverted to Islam. I think in a way, my dad was supportive of learning from others as long as there was a hard line when it comes to practicing with them and you genuinely need know what you're doing. All the outside school activities were more so for external programs to pick up team building and those type of skills. I always opted for raising money for the local homeless people, natural disaster and generally poverty struck causes instead of fund raising for the church or preaching duties.
As for students being pious, I can't speak for other schools but our school was split in two categories with me and a few more kids being the anomaly. 1 side literally
lived for the church and on the far end of this crowd you have the more 'militant' types. Vocally racist and sexist. I specifically remember this one kid asking the teacher if they're allowed to join the pope temporarily if he calls for a crusade against the Arabs.

And on the other end you had the live and let live types. Super liberal people and on the extreme end of it you had a few suspect kids. I remember there were these two boys, ultra suspect. I don't know if it was just kids being dicks, but there was a rumor going around of them getting caught giving each other blows during lunch. They didn't show up after. Right when the rumors started circulating they
both stopped showing up. They got pulled out for 'unknown' reasons. The teachers never told us why they left the school. Other than that, on the student end of things it was your average school, some drugs, bullying and a few teen pregnancies. The other school was a Catholic state school, that was the 'bad' school. I would always hear of the craziest coming from there. But state schools universally perform worse than public schools. But overall in their respective categories, they're both 'average' schools I reckon.
I wouldn't say that's out of the norm at all. The mean marriage rate is in the early 30's. Do you not live around White people?