I am pretty sure you can set your own DNS server in Android.
I am pretty sure you can set your own DNS server in Android.
I think most up-to-date OpenWrt routers can do later (with normal, unencrypted DNS requests), see https://openwrt.org/docs/guide-user/firewall/fw3_configurations/intercept_dns.
The model you mentioned (Flint 2) is supported by OpenWrt.
route ipv6 dns to a destination of my choice
Does this mean setting custom DNS server (so devices using DHCP picks up what DNS server you want them to use) or intercept DNS requests (MITM or use firewall rule to drop outbound 53 port requests)?
Without the need for versioning, I think rclone fits the description. For backup into USB drive / remote SSH server I would recommend rsync.