Which key fob can I use?

Hi everyone,

I picked up my first alphard and it only came with 1 key, the grey key which I think is meant to be the spare key.

I'm unlocking the car with the key in the drivers door lock, all the other doors unlock at the same time so central locking is working and knowing imports/Japanese cars I'm sure these vehicles came with all the extras including a remote central locking key fob and 2 keys.

I know I can get a new key cut then i'll have a spare key but can anyone suggest or link me to a decent key fob I can use?

either one that I can program or is it OK to use an original toyota key fob from another car?

I'm thinking a fob from another toyota might be interchangeable and can work if reprogrammed?

Many thanks

Andrew