This isnt some iMessage that is pre-installed that is full of 0 click exploits. This is FOSS that has been tried and tested for a few decades. Sure there might be some cases where someone didn't update software for an exploit, but you'd still need to have that specific software, and I imagine that you'd need to chain a few to make it useful.
I can't see how a Linux phone is more dangerous than an iPhone. (aside from social engineering scams)