This can be a good stopgap, but the solution is to lobby for a law that mandates free ONT/modem/router choice.
We have such legislation in NL and the ISP is required to make it possible to use your own equipment.
Coincidentally, I had my ISP register my Fritz!Box Fiber 5590 as my ONT yesterday, so I have it directly hooked up to XGS-PON with their SFP+ module (no more Genexis ONT \o/).
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