Hey Alexey!

 AV> Hardware part:
 AV> https://www.aliexpress.com/item/details/32754558554.html

Right now I only have one router working and it's a Supermicro SYS-1017A-MP
with a Ralink Technology, Corp. RT2870/RT3070 Wireless Adapter for the wireless
part.  It has two Intel Corporation 82574L Gigabit Network Connection to cover
both a internet and intranet wired connections.  A very nice little setup for
sure.

Your idea looks interesting and definetly affordable.  I'll have to investigate
it more.

 AV> Software part: GNU/Linux for MIPS (possibly OpenWRT), binkd, hpt.

I currently am running a bastardized Linux From Scratch on it, with hostapd for
the wireless connections, binkd on the internetted wired connection but have
had it running on the wireless as well.  I am using WeBeBashing instead of hpt
but have been thinking about hpt if things get heavy traffic-wise on
1:153/7001.  Both the wired and wireless connections aren't seeing enough
traffic to worry about it and if it weren't for WeBeBashing I'd be totally
bored with Fidonet and would have abandoned it ages ago.

 AV> Implementation thoughts: disable SSID broadcast, transfer only
 AV> encrypted (RSA4096+SHA2+Twofish256CFB) files.

I was doing a similar thing with wireless mesh with some success.  The problem
with mesh is that it is extremely selective about wireless chipsets and there
aren't many readily available that can handle it, which might actually be a
good thing.  However at the moment I have one neighbour who needs me to be
running hostapd so she can connect with her Android based smartphone.  Too bad
they can't mesh as that would definetly make them far more useful.  As is they
make good paperweights ... as long as they don't catch fire.  ;-)

Life is good,
Maurice

... Don't cry for me I have vi.
--- GNU bash, version 4.4.12(1)-release (x86_64-atom-linux-gnu)