You could create a stepped lambda function that emits topic every minute with the date and time in it, something like YY.MM.DD.h.m and then register one function handler for multiple topics, I.e. .0, .15,.30, .45.
I use this concept extensively in a few edge devices for which I don't want to build dedicated/centralized infrastructure. It works rather well. There seems to be some drift and the timing is not 100% accurate but is ok in my setup
I can't, or rather, I don't want to use lambda because my functions need access to both the DB and the open internet. The only way I can get that working is to add a NAT Gateway to my VPC which has a relatively high fixed monthly cost. :/
