Nebulous
Legend
That's what I recommend. There are hundreds of maps out there similar enough to repurpose and upload to the VTT. I even repurpose maps I already purchased through Roll20 that have all the dynamic lighting embedded.Do you want exact replicas of the original maps just in colour for VTT or are you looking for similar maps you can repurpose.
If it’s the latter, I can heartily recommend both Heroic Maps and Seafoot Games. Their patreons give access to a huge library of maps for VTT and many of they underground maps are spectacular. There’s a brilliant crystal castle map that would be perfect for the Rockseers and many others.