What is going on with that FP it looks like you are strating to rip it out???? If not it needs a huge clean up for sure . If you burn wood you need a hearth and sectionals are always IMO a poor choice for seating . In this case no way do you have space for one from what I can see. I need more info as to the actual size of the whole room and some clue as to the use of the space

I’d skip the sectional - a sofa and chairs gives you more flexibility. Def not a pro but I feel like most fireplace renos are expensive, often removing it entirely seems to be the most cost effective but it looks like you all use yours?

You can get a lot of help on layout from the pros on here if you show the whole room and add a measured layout

This is clearly a well used fireplace and you don't want to get closer to the heat. The hearth serves a purpose. Plus, you'd have to find matching flooring.

Make a small drawing of the space with measurements and we can help figure out how to maximize your seating. A sectional isn't going to get you as much seating as you think it will.

I got rid of a hearth in my previous house, but it wasn't a brick fireplace and it was in southern CA, so rarely/never used.

Is this your main home or a vacation home?

You cannot remove the hearth completely, it is required for wood burning fireplaces. You can lower it to floor level and use a non-combustible material, like the slate that is already on the top of the hearth.

With that said, if you remove the hearth, there is no guarantee the bricks behind it can be cleaned up enough to be presentable, or are even in a condition that you could clean them up. Unless you are planning to redo the entire fireplace facing, you may be opening up a can of worms.

I removed the hearth from our electric (never used) fireplace. But only after I found matching floorboards in the attic. This looks like a well-used wood fireplace and the hearth is a safety feature. I wouldn’t remove it.

You could paint the brick if the bricks don't clean up nicely. If you remove the hearth, I'd just reuse the slate like a previous post said and have painting the brick as a backup plan if things don't match well or are stained. I definitely would not stick a sectional in that narrow room.