Yes. You can still list items that are fulfilled by you after joining Fulfilled by Souq program.
Operational & Safety Guidelines at Souq Fulfillment Centers
Souq Fulfillment Centers : Locations and Contact information
What is Fulfilled by Souq (FBS)?
Listing and Creating FBS Shipping Notices
How can I register with Fulfilled By Souq?
Can I request to recall my Fulfilled by Souq products from your fulfillment centers?