Try to find a rev3, the cpu upgrade really is really worthy

Which hw revision?

If it is a ver3 it is the same I have, good for FW and red services, you can make complex setups.

It is a bit short on cpu for ips systems(suricata and zenarmor) , but it is able to do dns filtering via adguard or unbound.

100€ sounds good to me if it comes with AP, people here are happy with that brand

Good luck

Take a sophos second hand FW.

Intel nic, low power consumption processors and full opnsense support.

Go at least for 4gb ram and the most powerful processor you can safely get. It will come with a lot of eth ports too on top.

And it will cost close to 100€, probably less if you struck a good deal