For the Aoostar I got the 19V version of “UPS Battery Backup, 24000 mAh Intelligent Compact UPS with High Security for Modem (19V)” from Amazon,

and got the exact same in 12V for my router/modem

I’ve been running my Aoostar R1 for over a year now, no issue at all. ~14W at idle with the 2HDD in standby. 32G RAM, a low power SK hynix Gold P31 1TB NVME. I’ve re-used the pair of 14TB HDDs from my WD NAS and recently got a pair of 12TB refurbished HDD for ca 240€ to use the old WD NAS as a backup. I run Proxmox with a bunch of LXC containers (12 mostly) of which a pair of pi-hole, pair of VPN/hardened SSH, fileserver, home automation, Logitech media server, Jellyfin etc etc etc The R1 is not that noisy, never crashed once, does not heat up and is powered through a 88.8Wh mini UPS.