Change Slack webhook integration to Slack webhook URL (so other services which can emulate Slack's parsing to use this feature as well)
Instead of making the Slack webhook integration via the API, just allow users to put in a Slack URL. That way any other service which can emulate the Slack webhook schema can use the webhook feature.
As an example Discord has webhooks and if you add "/slack" to the end of a Discord webhook URL then it will parse the data as Slack does.
Currently I cannot use Updown with Discord. I also suspect that many other programs have an option to parse data like Slack so you could knock out a few webhook integrations in one simple step.