A proper UPS protects against bad power, surges, brownouts and reclosure events. So it’s not just about shutting down gracefully (but that too), but also protecting your expensive equipment.

Nothing wrecks your equipment and data faster than the power going off and on three times in 10 seconds.

Usually I reboot once a year, but in reality power outages limit uptime to about this anyway.

You need an EV1527 compatible transmitter (the receiver linked is the common EV1527 type).

Like this one https://qiachip.com/products/qiachip-wireless-doorbell-no-battery-required

Or this https://wiki.dfrobot.com/SKU_TEL0146_Self-Powered_Wireless_Switch_433Mhz