i've noticed that problem too, there is a solution which pico-8 managed to fixe somewhere. but i have no idea how he did it. i will update my post once i found that said solution.
Does Pico8 always scale perfectly when you resize it? I'm sure I can sort this out but right now it's low on the list. I think I'd like to add some settings that let you scale the window to better resolutions.
yes here an example how pico-8 behaved, i think you will get some hint with this example
i hope it does help you out :) unfortunately, i couldn't find any information about that system... but i do hope you will figure it out :)