After TRIMUI's recent success with the TRIMUI Brick, and the upcoming launch of their metal version (which is shipping this month), a rumour has it that they could be working on another device.
This information was leaked on Baidu and reported by NotebookCheck. The leak shows multiple renders of an upcoming device that looks to be a smaller and more compact version of the TRIMUI Smart Pro.

Titled the TRIMUI Smart Mini this has a more compact version and a 4:3 display with a possible size of 3.5" - 4", making it a great retro gaming all-rounder, if it can follow in its smaller, horizontal brother's footsteps.
These renders look to follow the simple, minimal TRIMUI look, and likely use many of the smart pro's components such as the buttons, joysticks, shoulder buttons and menu buttons.

Heck, likely, the speakers, the OS, the front end and the specifications will be similar too, simply with a new 3:2 display to capture the essence of retro gaming and to remove those black borders that nobody likes from Game Boy Advance emulation.
It makes sense from a business perspective. They have the moulds for most of the components, all it needs is a new shell, a new display and some adjustment to the motherboard and likely a smaller battery capacity.

As I write this, I am surprised TRIMUI hasn't done this earlier. Their devices are remarkable, and I can imagine many of their fan base would be more than happy to see this enter the... admittedly over-saturated playing field if it comes with some extra power.
All they need to do is make it competitive in terms of pricing in comparison to things like the ANBERNIC RG406H.
As of now, this is the only leaked information. Nothing has been confirmed by TRIMUI themselves, and likely won't for a while as they start shipping the Metal TRIMUI Brick.