There are ways to integrate SFDC dev org to dev org
SALESFORCE TO SALESFORCE
Probably the easiest one and offered out of box .
To connect two salesforce instance you will create Connected App in the transmitter or publisher org.And you will consume the standard REST API in the subscriber org or reciever org .
Take a look at one of my previous answers to dig deeper
How can i integrate one SFDC org to another SFDC using Rest Api
Using named credentials you can do in few lines .Check below blog
External objects in production come at cost but in developer orgs they are free .With new release you can write and read from external objects .
Check the below article to dig deeper
You will create an external data source as salesforce and in another instance consume the same