as may you already know the GPON ONU SFP transceivers only have 1GE (Physically) and only are capable to negotiated data-rates up to 1Gbps (1.25 theoretically) on the Ethernet side (LAN) even if they are capable to work up to 2.5Gbps (for downstream) on the optical side (PON) as described on the GPON Standards.
In the traditional ONUs (ONT or HGU) is possible to take the advantage of the 2.5Gbps data-rates (downstream speeds) because they have multiple GE interfaces (Physically) but even in this case, each Ethernet is only capable to work at 1Gbps.
Now, in the XG-PON, XGS-PON and NG-PON2 technologies are being designed transceivers over SFP+ interfaces to makes capable to work with Multi-GE interfaces on the Ethernet side also.
So, there not exist "magic tricks" to change that, I've recommend you to take a look at the standard definitions (IEEE 802.3ab - 1000Base-T) and (IEEE 802.3ae - 10GBase-xx) to understand better how it works.
Your ONU SFP is functional. It does what it was proposed for, inserting itself into an SFP or SFP + interface and directly connecting the physical link by optical fiber, by registering itself in a GPON tree. Within this perimeter, it is functional, 100% useful. It does what I bought it for. As such, it remains in my collection of ONU SFP (because I have, in fact, some)
But, and this is not your responsibility, it is not recognized by the Mikrotik CCR2004. This is sad. Whether we raise the question of activation at 2.5Gbps according to HGSMII, the question does not seem to arise with your ONU because, beyond the desire to activate it at 2.5Gpbs, the Mikrotik CCR2004 does not even recognize it . No doubt this is related to the reasons you cited in your feature request for which I voted for.
So, strictly from a business point of view, I am a happy customer. However, I cannot insert it into my Mikrotik equipment.
I do not hide that my main quest, to connect my fiber link directly without operator equipment, is linked to my desire to have the second Gbps that I pay to Orange France, but that the equipment does not allow me to use.
To achieve my goals, I needed to connect my fiber to an SFP interface, and your CarlitoxxPro does it, but not on my CCR2004.
If I have not been able to directly connect the CarlitoxxPro to my CCR 2204, which, I repeat, only understands 1 or 10Gbps, I installed, in a small low power server, a Dell N20KJ chipset card BCM57810S, dual SFP +, and I configured a bridge between the two. My fiber therefore arrives in my CarlitoxxPro, bridged to a 10Gbps SFP Single-mode Fiber interface, and this 10Gbps link is routed in my CCR2004 which takes care of the particular authentication of Orange France from my home (question of DHCP requests in COS = 6).
This is the reason why I affirm that my CarlitoxxPro module is functional, with PLOAM filled in and SN changed.
It is probably up to Mikrotik to include the right Linux kernel module patches to directly integrate the possibility of inserting the CarlitoxxPro directly. Unfortunately, there is no possible activation of 2,5Gbps by HSGMII on CCR 2004, according to the feedback I received from support after my bug report on the beta version which crashed by checking the 2.5Gbps box (yet present), for reasons described as material at this time.
With the 10Gbps bridge that I put in place, I broke away from the Linux kernel module types of CCR, to use a much more up-to-date 5.8 kernel on the bridge, and provide CCR 2004 with what it gladly accepts, a flow in a 10Gbps fiber optic link.
Now, thanks to this bridge, I can certify that the CarlitoxxPro works, and since it is only one of my almost eclectic collection, I have others that work. I don't have any at 2.5Gbps yet, as they are rare, but since some are known to be compatible, I won't be long. I will then only have to configure them on my workstation, which is also equipped with a BCM57810S card, then place them on the bridge, to achieve my goals. And the day the XGsPON fiber is deployed, I would only have to change the ONU.