Minimum HW requirements

What are your experiences with hardware ? I consider to buy some single board computers for my different homes, put a small linux on them and use them as Exit node.
What are the minimum requirements to this kind of hardware, so that possible performance problems (streaming and so on) only are issued by the internet bandwith and not by any HW bottleneck?

thank you very much

e.g. could a NanoPi NEO could do this job? Or is even an older Android-Smartphone capable to fullfill my demand???

CPU: Allwinner H3, Quad-core Cortex-A7, bis zu 1,2 GHz
Konnektivität: 10/ 100M Ethernet
USB Host: Typ-EIN x 1, USB 2,0
Micro-USB: OTG, für power eingang

OS/Software: u-boot, Ubuntu-Core-Xenial, Debian-Jessie
Farbe: blau
Material: kunststoff
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