Define your why (not"to make money"). If you aren't passionate (excited) about it, it'll be a chore, and likely never a success.
It seems like you're just floundering around when you mention multiple vastly different things.
That is an interesting perspective and I agree to an extent that I would find it to be somewhat of a chore.
Given I'm not necessarily passionate about my existing work (I tick all the engagement boxes mind you), is it a necessity to be passionate about a side hustle?
Not necessarily, but it's hard to make money at all at a lot of the side gigs (starting a blog, for example). If you're interested in it, you have several benefits:
1) The work itself will be better (like for a blog, the writing will be better), making it more likely to earn money
2) You're more likely to keep doing it, because you enjoy it, making it more likely to earn money (because stuff builds after time)
3) If you don't make money at it, at least you didn't waste time doing something unenjoyable, but hopefully enjoyed it as a hobby.
So it definitely helps to be excited about something and monetize it in some way, rather than picking something solely because other people make money doing it.