Metro phones are prepaid. They also have different policies to unlock. They will work but some may lack bands and or frequencies that would give you more stable service. Metro has less support and far fewer updates that tmo postpaid. There’s a reason that metro phones are far less than tmo phones.
You can search the support site for links to unlocking phones or contact Metro.
While both are essentially the same each is its own company.
Manage your T-Mobile account