I agree with Patricia! If you are wanting to achieve the look in your inspiration photo it will take a lot of work and it will be more expensive. You room as it is would be better suited for a mid-century modern style. If you were to go this route I might suggest shelving instead of more traditional built-ins. That should eliminate the need for removing the wall to wall hearth. Otherwise, remove the heart (or at least the portion on either side of the firebox), install new gypsum board on furring where it will be exposed and then begin installing your new built-ins. Good luck!

I just mean the style. We still have to keep the hearth. So it’s likely going to go over it in some way. The tv will go above the fireplace.

The tv is just there temporarily. It’s getting mounted above the fireplace after the built ins are done.

Worst place for TV is over the FP. Yours is too high for watching comfort as is your inspiration picture. Neither set up (yours & inspiration) are great for watching TV. Sitting sideways isn't all that comfortable. What do you want built ins for? Do you have great pieces to display?

something like this where the fireplace becomes recessed. lip over the hearth. do not put tv over FP tho put it to the left on a pull out swivel.

https://diy.stackexchange.com/questions/78109/electrical-for-built-ins-and-fireplace-insert