Ugh, you're going to give me PTSD...lol
I had the joy of managing a multi-faith global team for a couple of years. Did my best to cater to both general public holidays and religious observances, too.
1) I'm sure I didn't always manage it, but (as you say) people seemed to appreciate the effort.
2) My goodness it made scheduling a challenge.
In my years of management, I can relate to your pain.
I did my best to accommodate religious observances, working myself so another could celebrate their faith. In the rare instance that I couldn't, people still appreciated my efforts.