ColdShowers If it weren't for the recent battery situation and related uncertainty, I'd also suggest considering option #5: getting a Pixel 6a, which is still a nice phone (with its great small form factor), yet should be available very cheap now. This would give you the chance to evaluate GrapheneOS first without having to commit major resources.
But note that this option is currently suboptimal because some of these phones may have defective batteries, with the capacity about to be lowered through a firmware upgrade. So I'm not really recommending it: maybe unless you could get a 6a really for peanuts.
Regarding option #4, CalyxOS is essentially LineageOS with MicroG. If you're willing to compromise on security and all the other advantages GrapheneOS brings to the table, you might as well grab any other LineageOS-supported device and install MicroG on it yourself, which at least leaves you with more devices to choose from.
That being said, I've been using MicroG as well (still do, on my backup phone). It's a clever hack that served me well for years, and I appreciate all the development effort that went towards it. But in my view it's not something that should be a basis for a (commercial) solution, nor should it be considered on par with GrapheneOS.
GrapheneOS is in a league of its own, there isn't really anything comparable, and I'd recommend sticking with it as a choice (somewhat predictably perhaps, since it's my choice as well, which is why I'm even here).