One of these should do what you’re looking for. Each has a slightly different approach.

https://etcher.balena.io/

https://unetbootin.github.io/

https://www.ventoy.net/en/index.html

Play store, profile picture, settings, network settings, auto update apps.

There are options for auto update over wifi only, or over data,

It sounds like you’re looking for intrusion detection or prevention rather than antivirus.

Great list here https://github.com/sbilly/awesome-security#ids--ips--host-ids--host-ips

However it’s likely that these do not run on asuswrt-merlin out of the box and may require additional setup or hardware.

You may even be good enough by using the built in firewall on the router interface and making sure no ports are open/forwarded.

But, why?

ClamAV is a scanning engine that uses a database and heuristics to detect an infection.

Are you looking for an Anti Virus Scanner, or Intrusion Prevention System?

Hi, I would like to recommend LibreOffice over OpenOffice.

https://itsfoss.com/libreoffice-vs-openoffice/

https://www.libreoffice.org/

is it foss ?

Yes. https://github.com/aeharding/voyager

4.01Mb may be too small for a single block.