It seems, that R2 already has some code for HNAT:
#if defined(CONFIG_RA_HW_NAT) || defined(CONFIG_RA_HW_NAT_MODULE)
SFP GPON ONT works just as a simple bridge beside it does also authorization to OLT (look at one of link I sent)
all other things like VLANs, routing, NAT, PPPoE etc is done on connected router, like R2.
So, I'm looking for router with SFP connector for GPON.
Beside R2 (if HW team would add SFP) I'm considering also
But, beside it is slightly higher price than R2, I don't know
state of it's HWNAT, what is (IMO) must-have at GPON speeds.