Transformers Wiring To outlet cord
No problem, only question is how good you want it to look

Doorbell transformer, made to order has connector to go into an electrical junction box.

Head to home depot, or lowes - find an electrical box you like, plastic, weatherproof, metal and a cover plate for it

Add a doorbell transformer

A small pack of romex connectors (nmb might be the name on them)

a couple of wire nuts, yellow

A round extension cord that appeals to you.

Cut off the female end of the cord, and assemble as it appeals