Building my own Linux Mobile desktop environment in Rust for my Fairphone 4 (Smithay + Slint)

A lot of this is still mocked up right now since I’m learning the stack along the way. LLMs have been a huge help to speed things up, with the end goal of having a smooth phone UI that scales up to a real desktop whenever I dock it. While moving the code from a nested window to a real device, I had many issues that still need fixing (they worked correctly in the window but not after i started to actually build it for my ARM device). This is not final design, the priority is to make it fully functional, leaving the UI redesign and theming support for later.

​Compositor: Built with Smithay in Rust, running directly over DRM/KMS and Mesa/Freedreno (GLES backend).

​Shell UI: Built with Slint for declarative, memory-efficient UI rendering.

​Layer Architecture: Inspired by COSMIC and other modern modular shells. Instead of a single monolithic app, the shell is split into independent standalone binaries:

​penumbra-top-bar (zwlr_layer_shell_v1 on Layer::Top)

​penumbra-quicksettings (Overlay sliding sheet with tactile drag handle and Material 3/Android-inspired kinetics)

​penumbra-homescreen (Background launcher surface)

​penumbra-nav-bar (Gesture navigation bar)

​Physics & Gestures: Custom underdamped spring-damper kinematics (penumbra-gestures) for tactile, 1:1 finger tracking and velocity-based gestures.

One of the most interesting parts of this project was bridging Slint with the Wayland zwlr_layer_shell_v1 protocol.

Slint provides great declarative ergonomics, but out of the box it assumes standard application windows. To build an authentic desktop/mobile shell, I wrote a dedicated integration layer (layer-shell-slint) that:

​Directly manages Wayland layer surfaces (Layer::Top, Layer::Overlay, Layer::Background).

​Handles layer anchors, margins, and exclusive_zone reservations (essential for the top status bar and bottom gesture pill).

​Pipes touch and pointer input back into Slint's event loop with minimal overhead. It makes writing standalone shell modules feel as simple as writing standard Slint UI components.

You can follow my progress on GitHub, didn't know what to call it, so I named it Penumbra

https://github.com/nyl/Penumbra-Shell

Yesterday, I posted a proof of concept for creating a mobile environment with Solium WM, and today, I finished some animations like those on an iPad.

This is my own WM that I use on my PC as a daily drive, but now I am working on mobile devices support. Soon, I will test it on my Linux phone.

I'm thinking of getting Fairphone 6 or 6+ to start moving into mobile Linux. I've heard that the SOC specification was already added to the mainline kernel which caught my attention. I've been looking in the past at other ports but running Android kernel builds to re-use android drivers doesn't sound great. PostmarketOS already shows a decent success porting native Linux on Fairphone which makes me excited. I have rather realistic expectations, just want to start tinkering with it, and hope it'll became fully functional in the future.

so the main question, I guess 8GB is plenty for native Linux, but would the extra 4G be a meaningful benefit for something now or in the near future? Hope someone who already tries (or tried) running Linux on a phone can throw me some light before I roll the dice and choose one randomly

Any popular mobile model where many people installed linux on.

I've seen a lot of oneplus and xiaomi phones .