Maybe not in the countries you asked for but the south of France is worth a look. Nice is a great, vibrant city with tons to do and lots of access to what you’d need if you’re working. Meanwhile you can do easy day or weekend trips to surrounding areas which are awesome. Eze, Cannes, Antibes, Villafrenche, Monaco, and more are all super close by.

OP specifically asked for Spain as well though.

Depends entirely on what your use case is but personally I am doing some outdoor lighting soon and will be using dumb fixtures on a smart (lutron caseta) switch + motion sensor to trigger automations. Happy to dive in if you have questions.

You cannot just use deCONZ or similar with HomeKit. Doesn’t work that way. It’s just an antenna. You will need Home Assistant or similar to make the dongle work.