Can I use an unlocked iPhone as an iPod? Would I need a sim card?

Hi! I'm wanting to buy an old iPhone (maybe 3gs-4) so that I can use it for an iPod. I was wondering, if I was to buy an unlocked one off of Ebay, would I need a sim card in order for it to work? I would use it for listening/storing music, and for browsing the web.

Yes, Because the stupid thing will say NEED SIM CARD NEED SIM CARD, BUT any old sim card will work

As far as i'm aware you need a simcard only for initial install, but afterwards it will constantly bother you. Why not get an ipod touch 5th gen with cellular data?

Yes, you will need a sim card, as it can be accessed without it and do install Leo Privacy Guard in it. It will guard all your private stuffs, which you don't let your girlfriend to access.