Can we see a picture from further away, with a better overall view of the room? I'm curious as to why the bookcase can't be removed. I understand that you'd probably need to fix the drywall but I'm not clear on how it's attached to the fireplace. Removing the bookcase would be my first move, I suspect. I'm usually not a fan of painting stone or brick but would understand your motivation here. That said, I find the after in your first inspo pic much duller than the original stone. There's only the last inspo pic that suggests the stones weren't uniform.

Thanks for the feedback! I wish I could take out the bookshelf and put another window there instead actually. Someday maybe! The white wash idea is more of a temporary fix for the time being because I just really don't like the dark stone.

No, don't. Your deeply textured river rock wall will look nothing like the inspiration photos you posted; those all have cut stone faces and are already fairly flat. Yours will look like a jumbled mess with dark shadows because of the deeply recessed mortar joints.

Thanks for the additional pics. Ok, seems clear that the stone was added after the bookcase. Is the bookcase even attached to the wall? The additional pictures are helpful because we can see your living area is part of an open plan. In that instance, designing an element in isolation is even less of a good idea. Can you share pics without distortion? I think these pics are taken in pano view? Is that an opening to the right of the fireplace and if so, what's in the next room? Your plan here will depend on your budget, obviously, but I think you need to take the whole house into account and have a long term plan.

A lot of people here recommend Romabio limewashing for exterior stone and brick. I don't know the cost or the labour intensity so don't know if that could be a short term solution for you. Alternatively, I'd be looking into removing the bookcase and covering the stone with a new sleeve material rather than removing the stone.

While you may not be able to remove the bookcase, maybe you can have the upper part redone to modernize it. I’d have a carpenter come in and see about covering/replacing the scalloped parts.

Your inspiration pictures are not as attractive as your unpainted/unschmeared rock fireplace. Get rid of the bookcase and touch up the edges of the rock if it gets damaged. If badly damaged, add a low, simple bookcase in a light color which matches some of the stones.
As for the area being “dark”, additional or better lighting may fix that.
In my opinion, removing the entire fireplace corner would be better than any paint job which will just look bad.

You'll be able to keep the variations in the stone if you use a Limewash instead of just a diluted white paint

Adding mortar to the current installation is also an option.

Here is Emily Henderson's Blog about making over her fireplace.

https://stylebyemilyhenderson.com/blog/stone-fireplace-makeover-mountain-house

I think the last three of your inspiration pics look great and very natural, but that first photo is definitely not a good look (especially with the contrasting gray grout color). I would not paint the stone.

If you’re looking for more of an old world look, I think an over grout technique would definitely be possible with the stone you have. But it would be a painstaking job and take someone with a good deal of skill and careful attention to detail otherwise you will have a sloppy, unsightly mess. Your grout color would have to be carefully chosen as well.

That's a beautiful rustic fireplace, but for me it would be a cleaning nightmare. That said, your inspopix are not equivalent, as has been mentioned. Leave it as is until you can afford to remove it. Is the bottom of the bookcase made for TV? My focus would be on finding a way to eliminate the bookcase. Buy a long extension for your vacuum so you can suck the dust out of all those crevices.