The Pedaltrain Nano+ could get you 5 or 6 pedals, depending on the pedals. Next up would be the metro 16 or 20.
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I use a Cioks DC-5 on my PT Mini. That one and their Adam will fit under a Nano or Mini. I think other than the PT Volto (which is a rechargeable power supply) are the only ones you can mount under a Mini or Nano.