If you have nostalgia for this, check out Free Pascal. It's an open-source Pascal/Delphi clone, and includes a clone of the blue DOS Turbo Pascal editor that will give you the vibe you crave.

I used it for a few of the Advent of Code days this year, but man the nostalgia wore off. Both the limitations of the IDE and the verbosity of Pascal weren't "fun" to operate in daily coming from the modern world. But definitely sweet memories.

I think RHIDE still has source code available, even if it's 23 years since the last update?

Real problem with implementing such a terminal-mode GUI is that Unix/Linux terminals clung to a terminal standard which didn't provide all the features of an MS-DOS text mode program. In particular, it can't recognize the Alt key by itself, or Alt+Letter key combinations. Or Ctrl+Shift+Left/Right keys.

I keep a box with the manuals on my very previous bookshelf space. Turbo C

I have still all manuals from all Borland products, they were great.

In rainy days, I still browse through them.

For those that never saw them, they are available at the Internet Archive.