So then it becomes a question of which is easier:

1. Set up a Siri Shortcut "when alarm goes off, play Spotify". Haven't done it, but having been knee-deep in Shortcuts this weekend, I'm confident that it is possible, and (on latest iOS) not difficult even for a Shortcuts n00b. (For Android, I know Tasker can do this.)

2. Fiddle with buggy and not-maintained-as-soon-as-it-shipped application to set alarm clock. Application must run on a computer that, coincidentally, can serve as a full-function WiFi-enabled alarm clock and can set its own damned time.