What if the modular computing evangelists at Framework decided to make a handheld? YouTuber Pitstoptech has largely answered this question by building a "fully upgradeable gaming handheld" around one of Framework's upgradable motherboards. As it’s a modding project, rather than a professional endeavor, the result isn't as sleek as it could be, but the work shown (h/t Liliputing) still admirably illustrates the potential here.
Framework's laptop designs (Intel 13th Gen review) are best known for their modular properties. One of the key attractions is the ease with which users can replace their laptop mainboard to grab generational mobile platform upgrades provided by both Intel and AMD. Of course, the modularity cleverly extends to other parts of the laptop too, as well as the port selection.
Current owners of Framework laptops have started to see these upgrades appear for their computers, and have several choices of upgrades, as well as choices for disposing of their older and unwanted components. Also in April 2022, Framework started to sell its mainboards separately, to the wider market, sparking interest from makers.