I keep meaning to go and play the Underworld games, since I love the subgenre they pioneered (Immersive Sim). I'll get around to it... one day.
It's like you say, not exactly the same, but for CRPGs it's hard to go wrong with Baldur's Gate 3. It's similar enough to later Ultima in some ways that it might scratch the itch.
Elsewhere in thread is mentioned an Underworld remake.
I do not have the same complaint about them as I do Ultima VII. A good remake could still be an interesting experience today, with little more than a graphical overhaul and modern controls. Both of them have a mixture of exploration, combat, and conversation that keeps them engaging over time.
Ultima VII's problem is that it's just... one big fetch quest. The combat is a non-entity (in the original game, I gather some of the remakes have tried to address this but they're starting way, way behind the eight ball), and there just isn't much else there.
Ultimas prior to VII don't have that problem because combat is functional, so the essentially multi-genre nature of an RPG where each subgenre keeps the other from becoming painfully tedious is there, but by modern standards, probably still fairly unplayable. Neat ideas, you can see how later games picked up the ball and ran with it in various directions, but very hard to play by modern standards. For instance, Ultima 4 combat has modern TRPG combat in it to some extent... except no even remotely modern TRPG game makes "moving one space" an entire action on par with "make one attack", and for good reason.
It's like you say, not exactly the same, but for CRPGs it's hard to go wrong with Baldur's Gate 3. It's similar enough to later Ultima in some ways that it might scratch the itch.