KaiOS shows us importance of FOSS
About software and its distribution
In the years which software was not commercialized and copyright about software was not yet a thing. People were distributing software and its source code and users were changing the software to their wish for better usability. The term hacker didn't mean someone who breaks into servers but it meant someone who plays around with the software and possibly fix bugs or add features to make it more useful. Today, this is known as “Hacker in the MIT sense”.
Later came FOSS to bring the same advantages to the software world in the modern era. FOSS stands for Free Open Source Software. Strictly speaking, free software and open source software are different. Free here means freedom not zero price. However most pieces of software which are free software are also open source and vice versa. This includes those under MIT/X11, GPL, LGPL, MPL and many many other such these licences.
From a point of view, KaiOS is just a pre-built Lego, just like any other Unix-like distribution. It's a Linux distro. The main parts of this Lego are the Linux kernel which its job is communication with the hardware, the libraries including
libc which provide a useful and more abstract way to talk to kernel, and finally Gecko which on the top of it KaiOS applications, including the System app and the stock apps, run. There are also many other stuff like propriety vendor-dependent stuff.
Which parts of KaiOS are FOSS?
The Linux kernel used in KaiOS phones is under the 2nd version of GPL. GPL is a strong copyleft licence. Many other “userland” libraries have similar licences. Gecko has a copyleft licence but a weak one. Copyleft means you can take the software and use it and possibly change it. But if you want to give the software to the others, you must give them the software and the changes in source code form as well. So from a legal point of view, KaiOS manufacturers must provide users the source codes which are under a copyleft licence. For example Nokia has published source code of Linux, many libraries and Gecko.
But will giving you the source code make it possible for you to change the OS to your wish and deploy the new version to your phone? Sadly, the answer is not a total yes.
First, many drivers are vendor-dependent and propriety. For instance, my 800 Tough has a Snapdragon from Qualcomm. If you have a similar phone, you will find many stuff in your phone with
qcom in their name for various hardware features of the phone, including but not limited to Camera, charging, Cellular data and 3D acceleration. So where's the copyleft? The Linux kernel is under GPL which is a strong copyleft. Strong copyleft simply means you cannot combine propriety code with strong copyleft code. The trick Qualcomm has used is to implement minimal functionality in the kernel and do the rest in the user-land where it can have closed source code. Also not every part of KaiOS is strong copyleft. There is also weak copyleft which permits the combination as long as the original source code will be available. Or in other words, the open source part does not become closed source. Gecko uses Mozilla Public License or MPL which is of this kind.
Second, there are many “System” and “Stock” apps used in KaiOS which are not FOSS. If you want your own free KaiOS, you'll have to write your own version of these apps. Like Contact, Call log, messaging and Settings app. And the most important one, the System app which runs other apps.
Third and the worst problem is that even if you've got an OS to deploy, the problem is the deploying process! You'll need to write your version of OS to device's internal storage and make your phone boot it. It's not easy, simple or straightforward. Companies usually lock their phones to prevent this and frighten customers that if they try such these ways, their phone will go out of warranty.
Nevertheless, there has been attempts to port different stuff to KaiOS phones by using the Linux kernel and possibly other userlands. You can see Affe Null's Bananian project which ports Debian to the BananaPhone. I also remember Affe talking about running KaiOS 3.x on his port but it wasn't useful without hardware drivers and other apps, especially the System app. Last time I asked him, he said he is no longer working on Bananian and instead working on postmarketOS.
Note: postmarketOS is a Linux distribution for the mobile phones. It uses the mainline Linux kernel and Alpine Linux on the top. You might see a variety of different old or very old mobile phones, mostly Android ones, which pmOS supports them. Unfortunately, because of drivers being propriety and little manpower to reverse engineer and replace them with FOSS ones, there aren't many devices with very good support of pmOS.
So just the kernel being FOSS has enabled the community to port different stuff to these feature phones. And this shows importance of the kernel to be FOSS.
Which parts of KaiOS are source available but not FOSS?
Now imagine if we had source code of these apps under a FOSS licence, we could do much better and travel much further. Because the licence of stock apps does not allow re-distribution, legally we are not permitted to publish the entire improved packages or custom ROMs.
So if the ecosystem was FOSS-based and if the devices were not locked, KaiOS could be much better and it wasn't the only practical choice we have got on our mobile phones. And we see that even though the stock apps are not FOSS, and their sources are not available, we have made significant improvements to the ecosystem for ourselves and other users of this ecosystem. If locked phones were not locked, their users could have these improvements in their hands as well.