This is not entirely correct. The Nanopi M5 does not require a HAT/carrier board for the NVMe SSD, which the Raspberry 5 would need. Also, it has an integrated NPU with decent performance. If you want to use that, it has absolute killer value over a dual NVMe-Adapter with an AI kit for the Raspberry 5 (think Hailo or Coral). It also has two MIPI camera connectors.
I am only going by technical data and assume the performance figures are correct and usable in standard software, haven't yet ordered one.
You can decide yourself if these are benefits that you would profit from, but I think the M2 is currently the absolute best-rounded overall package for an SBC. The direct NVMe connector alone puts it miles ahead of the Raspberry in my personal opinion. I hate using adaptors over foil cables for complex/fast protocols. Just my two cents. ;)