The frequency that 6E to broadcast doesn't travel as well and in many cases walls and furniture can interfere with it and as a result carries less data over distance. If you're not in room where the router is placed you might experience slower speeds compared to what you're used to on your current system. That said if the router is in the room you're going to use the Quest then you could be OK.
Personally, I had a relatively expensive Linksys 6E mesh system and in the last few days I've gone back to my old Orbi 6 mesh because the speeds and latency across the house were much better / more consistent on the older system. No point getting 940 down in one room and 200 in the next and even slower speeds elsewhere when the old system gives me a consistent 600Mbps and a low ping everywhere!
Useful article here if you want to read up on 6E before you decide: https://uk.pcmag.com/networking/131082/what-is-wi-fi-6e
It should work unless Vodafone do anything funny like restricted the routers to a specific ONT (Fibre modem) but I doubt it. If that's the case you would be able to return it based on eBay's return policy because the product doesn't work. Buying off eBay is sometimes difficult because you might not have the opportunity to return if it doesn't work out (if you don't get the speeds and latency you hope for). If it does work it might need a bit of configuring to work with Vodafone, likelihood is that you'll need your PPoE credentials which you should be able to get by contacting customer service.
Surprisingly the Vodafone router has a decent spec, if it's cheap enough could be worth a try.
Good luck! 😀
