I finally got around to checking this game out and the game seems to have serious issues I am looking for some insight on.
Fresh install via GOG Galaxy and from the separate installer both lead to the bitmap showing (with the game's logo), followed by the bookshelf / main menu eventually.

That main menu has some kind of extreme lag/unable to interact with everything and the game is effectively unplayable.

Through the use of additional tools such as dxwnd and dgvoodoo/wine I have strangely managed to interact with the book to attempt to start a game but it is incredibly laggy still and not responsive to input.
Anyone know of a working Dxwnd config or understand why I'd have blacked out videos? Changing dxwnd to primary or buffer surface sort of makes the videos appear but they have that inverted colour/on half the screen and look horrendous, otherwise using openGL just gives a black screen.
Some massive amount of alt+tabbing or gaining/losing focus to the game window seems to get you responsiveness back of the main menu enough to attempt to get into a game. I've yet to be able to reproduce enough responsiveness to even get out of the main menu at this point...I'm baffled I even got into a game at all at this point.

Thoughts appreciated.

I'll share how I install Return to Krondor, as it works fine on my Windows 10 install. Hopefully it'll help you as well.

I don't use dxwnd for this game, only dgvoodoo2 and additionally I prefer to run straight from the rtk.exe as opposed to the launcher.

In any case:

Install Return to Krondor (I used offline installer)
Download dgVoodoo2_84_1

Rename krondor.ttf to _krondor.ttf, so that system font doesn't get messed up if the game crashes (optional)

From dgVoodoo2_84_1 copy dgVoodoo.conf and dgVoodooCpl.exe to main game folder

From dgVoodoo2_84_1.zip\MS\x86 copy contents to main game folder

In main game folder right click RtK.exe and choose create shortcut

In the shortcut's compatibility tab make sure "Windows 98/Me" compatibility mode is enabled and "Run this program as an Administrator" is checked.

Rename shortcut to something like _Play Return to Krondor, for easy visibility

Play game. And if you haven't played RtK before:
New Game, make sure to name Book so that you can continue.
Use Map from Krondor button in lower left to get to different zones.

Alas, this game never grabbed my interest in the same way Betrayal at Krondor did, so I never played too far in.
Maybe someday...