I've been working with various options, especially pixel shaders, on dosbox-x for XyWrite.
General conclusion: if you want the standard 25 x 80 textmode, you can get things to look as good as they did in regular DOS, before we used NTVDM. If you want the size and quality of screen display you get with vDOS-Plus, you can't get it. And if you want 132 x 43 or 50 or 60, the display will be irritatingly bad.
Pixel shaders, specifically: Wengier wrote that there would be an open gl option on the menu that says "select pixel-shader" in the .83.7 version, but I can't get it to appear.
The regular pixel select menu item brings up an explorer-type open-file window that has its filetype set to "D3D shaders" (what that means is unexplained, BTW, but it seems to want files with the extension .fx, which are shaders for some game). You cannot change that limitation in the open-file window. There is no "all files" option.
Also, you cannot easily test the effect (if any) of the .fx shaders it finds, because as soon as you do "open" on one of the files, everything goes back to zero, and you have to mouse around through several levels of things in order to get to the next shader to try out.
There are many, many options under "Video" (and under "Render" in another dropdown) with names that are opaque to me, like "Overscan" and "scaler" and the options under "Compatibility." I couldn't adequately try out things, because there were far too many permutations available (a good thing, but . . .), and as soon as you try one, as I said, you have to back to ground zero.
Someone with the requisite advanced knowledge can probably sail through these options, but as for me, I'll stick with vDOS-Plus.
My thanks to Wengier for supporting such efforts as I was able to make, but huge thanks to him for developing vDOS-Plus.