PC Peripherals Need a recommendation for a UPS to handle my homelab

Hello,
So I need a UPS (600VA?) which will keep the following devices powered on

1. Raspberry Pi 3B+ with a 2TB external hard disk - which constitutes my OpenMediaVault setup that runs Plex and a basic file sharing within the network
2. Dell Optiplex 3050 Tiny PC (i5-6500|16G RAM|256G NVMe WD Boot drive)- which runs my HomeAssistant bare metal (there are plans to shift this to a ProxMox setup, as I experiment a bit with other containers/VMs)
3. Asus RT-AC66U B1 - My primary Wifi Router, whose 2.4G network I am using for my DIY home automations and the 5G is used by the smart TV/phones and laptops
4. The included 5G dual band router/modem that came in with the Hathway connection

The intent is for the system to be able to comfortably run for a couple hours on UPS, in the event of a longish power failure. The ability to run even low loads and not turning off when the connected devices are idling is crucial and non-negotiable. The ability to silence/disconnect/muffle the beeps on battery power is greatly desired. Reliable unit, with a user serviceable/replaceable battery unit is needed.

Thank you for looking at this - now hit me with your best options! Think budget, because I am a super cheap guy!