Torrentleech is open rn

https://www.torrentleech.org/user/account/signup

Use code FLREFUGEE

Hdparm has 2 -(Yy) flags that should work for you

If that's your goal I would set the apm on the disk so it spins down quickly when not active.

hdparm -B 50 -S 30 /dev/disk

For Aegis it means when you go to select a folder location once you have before installed and setup on the device it will show your nextcloud as a storage location on your phone you can set aegis to upload backups there automatically

Not sure if your eero can do this easily but you probably want to use DHCP option 6 so your router will forward the DNS server you select to all clients. That's how I do it on openwrt.