All thanks and regards to mxrch.

Here is a preview :

If your target has a Net-SNMP instance with the "extend" functionality, and you got a SNMP community string which gives you write access, you can use this tool to automate the process of sending commands with the SNMP RCE.

The tool automatically put you in your path to simulate a real shell.
You can also use all the commands you can imagine, apart those requiring a fully interactive shell (MySQL, Vim, Nano, etc.)
Not compatible Windows, sorry.

To run on OpenWRT you need configured snmpd and next packages:

opkg update
opkg install coreutils-whoami coreutils-base64

sudo apt install snmp snmp-mibs-downloader rlwrap -y
git clone https://github.com/wimark/snmp-shell
cd snmp-shell
sudo python3 -m pip install -r requirements.txt

$ rlwrap python shell.py <IP> -c <community string>

If you need to send longer strings, like your SSH public key, please use the legacy.py version.
The characters limit to send is short (SNMP Limitation).
Tips : use a ed25519 SSH publickey, not a RSA one, it's shorter.

Usage: shell.py [OPTIONS] IP

  Simulates a terminal over Net-SNMP "extend" functionality. Be sure your
  SNMP Community String has write access.

Options:
  -c, --communitystring TEXT  Community string for SNMP
  -v, --version TEXT          SNMP version (1/2c/3)
  -ss, --snmpset TEXT         Path for the snmpset binary
  -sw, --snmpwalk TEXT        Path for the snmpwalk binary
  -h, --help                  Show this message and exit.

https://mogwailabs.de/blog/2019/10/abusing-linux-snmp-for-rce/