If your devices are low power like a NUC, recycled laptop, DSL/fiber modem or NAS they'll likely accept 12V as input (or 12-19V for most Intel NUC for example).

If your devices are low power like a NUC, recycled laptop, DSL/fiber modem or NAS they'll likely accept 12V as input (or 12-19V for most Intel NUC for example). For these I wonder if instead of a UPS: buy two LiFePo 12V batteries with included BMS, two battery charger (AC to 12V DC), so you get a redudant 12V bus where to plug your devices. If above 12V is needed add two DC-DC converters eg 12 to 19V to add a 19V bus. Same for 5V. It shoud work and support failure of any one of the parts?