Ok, I'll give it a shot.
Smalltalk environments don't typically have "configuration files" because it's so much easier to just directly manipulate the configuration parameter. Interactive development- the kind impossible with anything but the most specialised of IDE-- simply makes "config files" obsolete. Take a look at the seaside configuration guide[1] to get an idea what this is like.
In k/q[2] we also don't typically use configuration files, but for a different reason: Every type can be serialised over network or onto the disk, and when it's written to the disk it's usually in a format we can mmap() and access transparently. This is how q is also a database -- the data types q supports also includes tables.
k/q also has a built-in event loop that's not dissimilar to what you get when you run nodejs with the debugger port open except it's fast, and it's the regular way k/q processes communicate with each other.
What typically happens is that a table is designed for configuration, and we just expose it to the UI. Production environments are usually locked down so the only UI is to edit existing configuration parameters (and those are permissioned accordingly). These UI are typically quite general for any k/q data type, so they're quite rich and easy for people to use.
Then parts of the application interested in configuration just query the appropriate configuration table - this is only about 1000x faster than you would expect connecting to a remote database, and in many ways it's similar to a python application just storing its config in an sqlite database, except SQLite doesn't let you have a table as a data type so you can't put a table into another table, and you don't have tooling around comments and advice like you do with k/q UIs.
There are other places if you look carefully: Environments people have used (even beyond thirty years ago) that didn't have configuration "files", often had interesting and useful solutions to storing configuration. People tended to build configuration into part of their application, and so the legacy of that has tended to be excellent tooling instead of novel file formats.
[1]: http://www.shaffer-consulting.com/david/Seaside/Configuratio...
[2]: https://kx.com/