Consumer grade NAS hardware friendly to alternative OS installation?

Hi there, I have lots of experience with Linux, but I hate messing around with hardware. I need a new NAS to replace the very old and extremely slow LaCie NAS that I hacked into running Debian with OpenMediaVault. That modification was necessitated by LaCie not offering updates for their NAS OS, so I’m leery of NAS manufacturers’ software and I mainly just need some low powered hardware that is specifically made for NAS use. I really don’t care much about performance, as anything will be better than what I have currently. I just want something that:

  1. Has 2 drive bays.
  2. Isn’t locked down, so I can easily install my OS of choice from a USB stick or maybe a netinstall. I don’t want to mess around with locked bootloaders or setting up FTP and DHCP servers on the LAN to make it boot off the network.
  3. No special hardware required, I don’t own an external monitor or a VGA cable or an external GPU. I need to be able to write the OS image directly to the boot disk, or I could connect to the OS installer over SSH.
  4. No hardware modifications required, at most I would be willing to open the case and swap out a USB pendrive, but I would prefer to even avoid that.
  5. Support for OpenMediaVault (either Debian + OMV packages repo, or a dedicated OMV installer ISO, either way is fine) or better yet TrueNAS.
  6. How much of a power consumption difference is there between an ARM v8 CPU and a Celeron N4xxx? And what about thermals? (This is for a very low-demand occasional home usage scenario. It will be always on but only occasionally accessed.)

Thanks in advance!