I found that we can migrate processes from one Appian environment to another by

AFAIK, this is the best practised way of migrating the instances,and I dont think there might be a way for doing it... May be Other practicioners have some thoughts

That would be the only way.

Unless you have the ability to launch processes based on data in a DB, in that case as long as you bring the data from the DB you can launch your processes, but at this point they become new processes not the old ones, with the same data from the DB but new processes.

Thank you Harshav and Eduardo for the reply.