Please provide a full log: ssh in, run "pastekodi" and post the URL.
I don't have any WS2812 LEDs here so can't test with real hardware, but just adding the dtoverlay with default settings shows both the rp1-pio and ws2812-pio-rp1 drivers being successfully loaded:
Code
rpi5:~ # dmesg | grep rp1
[ 1.978635] rp1 0002:01:00.0: bar0 len 0x4000, start 0x1f00410000, end 0x1f00413fff, flags, 0x40200
[ 1.987721] rp1 0002:01:00.0: bar1 len 0x400000, start 0x1f00000000, end 0x1f003fffff, flags, 0x40200
[ 1.996988] rp1 0002:01:00.0: enabling device (0000 -> 0002)
[ 2.003186] rp1 0002:01:00.0: chip_id 0x20001927
[ 2.395815] genirq: irq_chip rp1_irq_chip did not update eff. affinity mask of irq 161
[ 2.712353] rp1-firmware rp1_firmware: RP1 Firmware version eb39cfd516f8c90628aa9d91f52370aade5d0a55
[ 2.722320] rp1-pio 1f00178000.pio: Created instance as pio0
[ 12.224635] /axi/pcie@1000120000/rp1/spi@50000/wm5102@0: Fixed dependency cycle(s) with /axi/pcie@1000120000/rp1/spi@50000/wm5102@0/ldo1
[ 12.422735] ws2812-pio-rp1 ws2812_pio@4: Instantiated 60 LEDs on GPIO 4 as /dev/leds0
```BTW: We can't build rp1-pio as a module as that would result in the RPi5 DPI DRM driver being built as a module instead of builtin to the kernel - which means DPI displays wouldn't have display output during boot. If building rpi1-pio as builtin indeed is the culprit then that's a bug in the rp1-pio or ws2812-pio-rp1 driver and should be reported as an issue on the RPi kernel repo.
so long,
Hias