Thanks for sharing your experiences. In fact here there are shops for second hand devices, but considering I need the phone to last for at least 5 years (for the uni degree), I don't think a second hand option seems very appealing to me, as probably the battery life of the device would be reduced and I don't know if it could be unlockable.

In any case, I could buy a new 7 series but the shop where the discount is offered only has the 7a and the 8 and 8 pro. The discount for the 7a is only 50€ because it is a different offer instead of the 11/11 one (the store says it's a black friday offer, not the 11/11), so it is 459€.

Google says it'll get guaranteed Android updates until at least March 2026, and security updates until May 2028. The 8 series get both Android and security updates until October 2030.

I have seen what you said that Graphene hinted that the 7 series will probably get Android updates until their end of life, which is good to hear.

I have been struggling with this decision for some months, and you're right that nowadays phones are too overpowered and have processors that are better than needed. So the decision is to either get the 7a for 459€ and have 5 years of support or the 8 for 623€ and have 7 years.