I'll try to make it more clear: PNG format supports a lot of different combinations of channels: if you want, you can read more in depths in the format description.
Generally people care about two types: PNG8 (8bit per pixel, 256 colors) and PNG24 (24bit bit per pixel, Truecolor). Note that when you have a document in Photoshop that says 8bit, it's 8bit ...
The issue has not a thing to do with color spaces. It is about transparency...or alpha. Use BMP format. You cannot readily composite using chromakey or alpha blending with any other format on Windows based machines.
Broadly speaking there are two schools of thought on file-format design.
One is that you should have lots of options to give lots of different users what they want. The problem with this approach is that compatibility becomes a problem. Just because a program advertises support for tiff files doesn't mean it can open your particular tiff file.
The other is ...
No, SVG files are not sensitive to indentation or line breaks. They are sensitive to certain spaces (such as the space between <path and d in <path d...). You can run an SVG through a minifier like SVGOMG and see for yourself that indentation and line breaks are removed.
Because PNG is a lossless raster image format developed for the web, and ultimately for display screens which are RGB.
However the format was never intended or designed to be a print format, and therefore doesn't need to support CMYK colour, and so it's entirely the wrong format to use for CMYK printing - i.e printing where separations are required ...
Look at it this way: PNG was developed as a replacement for GIF and so generally to be used in digital work, which means RGB (screens use RGB). And yes PNG is limited to RGB. While CMYK is a print-specific model available in JPG**, TIFF, PSD and some other formats. Read:
Open the file in Google Chrome.
Then Control click the image and copy the image.
Open Photoshop and create a new page from the clipboard and set the resolution you need along with the colour mode.
Paste the image and save the file to what ever format you need.