I would not say recommendation, no. It’s going to be an unattractive, imperfect solution. But it’s an option. Frankly, were it me, I would rearrange the room so that I could optimize my speakers as much as possible and have that OLED hung so its centre hit eye-level.
If you want to keep the screen at the fireplace, as well as improve aesthetics and audio performance, @Ghost’s idea is the way to go. Just get an acoustically transparent screen so that placing speakers behind it won’t matter. All the necessary kit will be costly, though.
120FPS should be fine unless you are playing competitive shooters at a high level.
Sorry, I can’t offer a guaranteed win here, but surround sound is difficult to implement with rhe fireplace in play. Hopefully, wherever you place the centre, your AVR’s room correction will help get the sound to be pleasing.