Are you in the US?

Might be a lot of hassle – not sure what you’d want for it.

But do I need to get the exact same chainring sizes?

If not this seems like a good option perhaps:

https://www.ebay.co.uk/itm/FSA-AFTERBURNER-386-BB30-DOUBLE-CHAINWHEEL-MTB-CHAINSET-40-28-175mm-10-SPEED-NEW-/391713924272

FSA Afterburner 386 BB30 crankset

It’s 40/28 vs the 42/27 I have

So pretty close.

And I believe should be an upgrade over the FSA Comet 386 BB30 crankset I have fitted.

Might have to call some bike shops otherwise, as can’t find answers on the web despite searching.

I did ask Halfords, where I got the bike originally, but they said to get it online as they’d charge a lot more heh.