Rasbperry Pi is a popular choice as a SoC / SBC Linux board. But you have to use their custom linux kernel. Are there Linux boards with decent mainline Linux kernel support?
Just google x86 SBCs and skip ARM. There are a bunch of options using AMD and Intel SoCs such as ODROID-H3.
You most likely do not want to run a mainline kernel / system. Run Armbian instead, it is Debian optimized for SBCs, it has a very good track record and sometimes is the only option after manufacturers stop creating images for their old boards.
Generic images / mainline kernel might underperform in your board, the GPIO and other low level components will, most likely, not work and you might burn your storage as logging and other I/O intensive operations aren’t tweaked for SD/eMMC. Armbian aims to fix all those issues and provides continuous system and kernel updates long after the manufacturer stops doing so.
Armbian or DietPi.
Armbian or DietPi.
OP asked for hardware, not a new distribution.
my info could be out of date on this, but the last time i looked into it, the khadas vim3 was the most powerful arm sbc with mainline linux support.