I've just bought MBP 2017 with 128Gb and I'm new to macOS. I know that I can use external HDD or sd-card to store and run apps from it. But I want to buy home NAS. Question is can I configure and use NAS so powerfull and efficient as external HDD or even like 2nd local mount drive? I mean run apps or games from NAS or work with files not downloading to MBP ssd? When I am at home, my connection to NAS would be by ethernet to get the most speed, when I'm outside I have stable 4g-connection.
Yes and no.
Can you technically do it? Yes, you can. You can mount a volume on a NAS device in the same way you would an external storage device and offload your data and applications there. They would even run from that volume.
Would you want to? No.
First, just comparing USB 3 with Ethernet, you're opting for a connection that's 1/5 that of USB 3 (Ethernet = 1Gbp/s; USB3 = 5Gbp/s). Then, if you're intending to run this over 4G LTE, you'd be going from 5Gbp/s to 50Mbps - 1/10th the speed. This is not practical in any sense.
Get a high quality external USB drive for supplemental storage and keep it with you; it's cheaper and more practical.