I would start with a much more colorful rug it does not have to be boho but needs color. If that is real plant go for it if fake the garbage is where it belongs . I am not a huge lover of coffeetable stuff so a simple orchid real plant is all I woudl do. Can we see the other walls just post more pics in a comment do not start another post .This type of rug gives you some colors to pull for pillows IMO a bit larger than the ones yu have and remember if your guests need to remove pillows to be comfortable then you have too many

Yes the plant is fake but the fiddle fig tree is real
Here are the other walls and layout

Pillows are definitely easier to replace than artwork, but I agree there's a lot of cool nuertrals in the space. Given all the you may really enjoy having something more personal and with a story and meaning on the walls--I think something really inviting and with some texture would be wonderful, maybe an Emil Lukas thread painting?

So i would hate that colorful rug -- but so what?

I think one flat piece of art in a frame is not going to make the statment needed there given everything else going on in the room volume-wise. If you can't find something sculptural you like, and if you don't care for fiber art, then I would think more in terms of 4 works or 8 works.

I wouldn't do framed photos (unless amazing abstract color photos?) and I wouldn't do botanical drawings.

but i'd be hunting for a statement piece

how about this beautiful architectural fragment?

https://www.chairish.com/product/4822177/antique-architectural-fragment

flushmount?

https://www.horchow.com/p/lucas-mckearn-trellis-3-light-flush-mount-ceiling-light-20-cprod168880054?childItemId=NMHF25M_5I&navpath=cat000000_cat1590731_cat29220749_cat7930732&page=0&position=64

these are pricey but I think they'd look nice as a replacement for your plain square pillows if my computer isn't deceiving me

Tulip Garden Pink and Green Handmade Luxury Pillow, 16"x16" · More Info

www.society6.com - has reasonably priced pillows and artwork.

You might consider looking through some designs on here. Please note the rugs, artwork, and lighting used in each design included below.

European Country Flair · More Info

Bright Transitional Refresh · More Info

Scandinavian Modern · More Info