I've been looking around a bit for something like this, expecting many people to know more than I.

First:
Modding Ultima 8. Has it been done? I know that the file formats have some mild documentation floating around, and the source port Pentagram exists, does the work used in these mean that it is possible to add new quests/content to the original game? I'm particularly interested in adding/editing maps, dialogue/quests, and a handful of NPCs.

Second. Ultima 9.
Does the 1.19h patch include the changes for Freedom Mod? I haven't been able to find out if that was ever a released thing, but I am interested in learning how open ended the current version of Ultima 9 is, as well as what the compatibility issues between 1.19h and Beautiful Brittania (which crash the game when combined for me) are.

Third, and also Ultima 9,
What progress has been made, map editing wise on this game? I'm interested foremost in simply upscaling the overworld by a multiple of three, and rearranging locations to fit onto this new worldspace. I'm aware that some mapping has been done, and I'm willing to do any I need to do myself, but I haven't been successful in finding documentation on this issue.

If someone knows the answers to any of these, could they enlighten me?

I have not heard of any successful attempts to mod Ultima 8. I believe that there is no longer any support for Pentagram, but there is support for the Ultima 8 engine in ScummVM. If you were to attempt to learn how to program and then learn how to mod Ultima 8, I would suggest you contact the team at ScummVM so you can use their source code to try to start modding Ultima 8 using their source code. I don't think modding tools for Ultima 8 exist though, so you would probably need to be pretty savvy at coding in order to adapt the Pentagram source code to create mods for Ultima 8 that would actually work.

You can find some abandoned fan projects for Ultima 8 at ultima8.ultimacodex.com, which shows many attempts to fix/mod/remake Ultima 8. You can also find some abandoned projects for Ultima 9 at ultima9.ultimacodex.com.

There have been many attempts to "fix" or "mod" the Ultima games over the years. Some highly successful (e.g. Exult, Nuvie, xu4, Pentagram) and some...not so successful. Good luck!

Just want to add, that Pentagram is the "subengine" running Ultima 8 in ScummVM.

If you are interested in remaking Ultima 8, Exult Studio might be an option or - rather sooner than later - OAx6 (that might turn out to be more of a demake though) ...just saying :-D

other than that: what bliznik said :-)

Naturally scummvm doesn't get to run the host of games it supports out of thin air - scummvm is just a collection of game executables rolled into one and all using the shared frontend.

Many of those started life as completely unrelated projects - Pentagram is one example.

They even briefly discussed absorbing Exult as well AFAIR

So my hope, if possible, was to do anything I did in the original engine, more of a fan expansion or "complete version" than a remake. Mostly all I have mind is quests and regions for 8, with some very loosely tabled stuff for 9. I do have an outline for a multi-chapter storyline, but none of the stuff would require changes to the basic mechanics of the engine. (Perhaps Ultima 8 requires that, but that's not my goal.)

I'm just interested in content because that's my expertise, and my vision has never been to make a "my take on U8" anyway (though obviously due to the lack of story documentation it could certainly be called that), but I was just curious where to start looking for that information to start kind of thing.

(The reason I was thinking of Pentagram is because obviously, if the file formats can be read by a custom engine, then they can be read by other things, and therefore the content can be customized. But I don't want my work to require Pentagram, persay, if that makes sense?)

Thanks again all for the help!