Do these apps work on my Garmin watch?

Perry states that all five have been tuned across a wide range of Garmin devices, with recent fixes for the Venu 2S, Venu Sq 2 Music, Forerunner 265S, epix and fenix 7 variants, and a crash fix for the Vivoactive 5. Compatibility varies by app. Check the Compatible Devices tab on each Connect IQ store listing before installing.

Each carries a free trial before payment. Battery Monitor and Alert runs for 36 hours, each of the four watch faces for one day. After that, each is a one-off purchase through KiezelPay, which does not sell subscriptions: $1.25 for Battery Monitor and Alert, $1.50 for each watch face.

Do I need my phone with me for these to work?

No. The Garmin Connect IQ phone app installs and configures each one, but all five then run on the watch itself. Leave the phone at home, and they behave the same.