Lightroom is fairly easy to learn. I used Photoshop from 1997 through 2013. In 2013 I got Lightroom...since then, it takes a terribly messed up image to "require" Photoshop, for me.
There are a number of raw image converters: Nikon has its own; Capture One has its own; there are independent, smaller raw capture converters that will make you a 16-bit or 8-bir .TIFF file that can be edited...
There are "free" apps and also "paid" apps...
Depends what you want to do; image editing at the pixel level? Photoshop is great for that! Want image catalogue AND image editing, fast? Lightroom is excellent at that.
Want to be able to ingest ,tag, and caption thousands of images per month? Photo Mechanic would be better than Lightroom, by far.