Using parcel to combine one main.js form module, but still having 'real' ES6 Modules in addition.

[iDad5]

Hi,
What I want to do seems easy at fist glance, but gets rather complicated in the real world.

I have a (right now) small web-app. For reasons a bit complicated to explain, what I want ist this:

I need a main.js file containing all the basic functionality, I want it to be one single file. (I don't cars for minification).
The main file is already about 3000 lines long, and I really would like (need) to have it split for development.
I program in TypeScript, using VS-Code.
For the first stages I just used a tsconfig.json with outputfile set. Next step i want to ad ES6 or even ES2022 Modules for separating individual functionalities per client/customer etc.

tsconfig with modules for ES6 enabled does not allow outputfile. I went for two different tsconfigs in the main folder and in the modules folder, but as soon a one import statement appears in the main folder's files, the TS compiler ignores the tsconfig and won't compile.

So the only option for me right now is to import export the files in the main folder as ES6 modules too. So I end up with around 10 imports and that number of additional http requests.
Which I don't like for that reason alone, and the deployment process, and the sometimes need for browsers without ES6 module support - where we will provide only the main.js functionality anyhow.

So what I'm asking, as I simply wasn't able to understand that by doing research including reading a lot of the docs :
Can i use Parcel with a reasonable overhead to my development process, to get all the (TS) modules in one folder merged into one file, while keeping them as separate modules, when they are in a subfolder? (Doing the merge with the transpiled js files only would likely also work.)

(PS.: I don't want to and don't need to use Node.js of any other library.)

PPS.: Thanks for your time. And If you have any other suggestion for tools or simply setups, compiler options etc. that you can think of, I'll be very grateful.)

[mischnic]

By "all modules in one folder merged" you mean something like concatenating them without anything else? So you're using global variables a lot?

The usual workflow would be to use imports and exports to build your app (in a hierarchical way), and have a single entry point which you could then pass to a bundler to create a single output file.

[iDad5]

Well, I do work a lot with classes which in a way qualify as global variables if you will.
The thing is, that bungling everything into one output-file I could easily do with the outputfile option of the ts-compiler. But I want the 'special features' in real modules as separate files, I love the concept of the ES6 modules, especially the way they are 'encapsuled' that potentially makes it a lot easier to develop them and the deployment process will be better for our needs.
Actually right now all instances of the app use 'physically' the same main.js that way we have bugfixes etc. deployed very easily. Almost all of the 'special features' need a local data, that we provide in a js - this file could potentially import as module, or the module could be loaded at runtime as ES2022 form the main file only if needed. So outing everything into one file won't do it.
Going for the native ES modules is a decision that I expect to be more and more beneficial over time.
(We do not and cannot use server-side programming for a lot of reasons)
Thank you very much for answering.