How can I turn this into a sewing cabinet and storage for sewing notio

We did a similar thing in my sewing room... but we did a drop leaf table that is supported by a drop leg (there are hardware brackets that lock the let in place, when down). A drawer or slide out will not support the weight of the machine or stand up to the vibration when the machine is running.

A fold out shelf that is supported by brackets or chains could work ... but the fabric might get caught or tangled up in them.

I would also make drawers to fit in the two spaces below the TV

The fold down table could be used as a door to keep the machine(s) dust free when stored (and hide any mess)

Add a flat 10 inch board shelf that's sanded very smooth & painted or wrapped with contact paper or perhaps a pre made melamine shelf, to the front of the TV shelf in cabinet. Attach the shelf to the cabinet using small hinges evenly space & put on "top" of both shelves so that extended shelf will fold to inside of cabinet for storage.

To support extended shelf, add shelf braces fancy or plain triangular shaped with top edge being at least 8 inches deep to support shelf with machine weight & work pressure. Attach at least 3 of these braces to sides & center cubby supports using hinges that will allow you to fold them to inside of cabinet when you're ready to put everything away.

Use baskets to slide into cubby holes for storage & supplies organization.

Modifying your cabinet in this way will allow it to be used for sewing, computer desk, etc & still be able to close doors of top section to hide machine etc.

You could also add a shelf inside top section of cabinet OR mount thread holders to keep those spools neat & at handy reach.

Hope this gives you some ideas.

I'm sorry I no longer have the piece or photo. I can maybe draw you pic or diagram if that would help.