I started using Krita instead, and it's a good replacement without being so utterly different.
I know Photoshop have some "content aware fill" and things but that's just their re-branded name for neural networks that are already open source, it's just a matter of time before it's available in Gimp. I might even consider writing those plugins too but my time is limited.
RGB color in Gimp is fine for me because I only use it for photo processing, and cameras shoot in RGB so you aren't losing any information by doing your photo processing in 16-bit or higher RGB.
You can do color space conversions to CMYK after that stage.
On an interesting side note, realistically though, I've found the vast majority of people I've had to work with don't understand the difference between RGB and CMYK and just want "PDFs" and don't necessarily let me choose or interact with the printing agency directly, or the printer is some friend's wife's father's friend's friends' friend's company on WeChat that is going to be doing the printing at 1/10 the cost of every other commercial printing agency out there and they've chosen to use that company and it would look silly of me to suggest to use a company that costs 10X more just so I can get proofs. In those cases, I've found that if I don't have access to proofs, these days, RGB PDFs often seem to get more consistently rendered than CMYK PDFs.
#Monopoly
Any advice, alternative PDF editor for Windows?
If you mean desktop publishing software that outputs a high quality pdf scribus works fairly well.
When I deal with government documents, visas, etc. I frequently need to produce 200-page PDFs that contains bank statements, utility bills, or other documents that arrived as PDF or were scanned into PDF. Some of those were scanned upside down, and then you might need to compress or split the resulting doc because of file size limit. So I need serious PDF editing software to deal with this - converting from PDF and back ruins all the official documents and leads to problems.