I never used it myself, but rather than a dedicated alarm clock app, maybe look at tasker?
Looking at their website they actually list your use case as an example of what is possible
wake up with a random song from your music collection
(Third point under “usage examples”)
I’ve read somewhere that horse mats made out of rubber are pretty good flooring for home gyms and cheaper than something marketed towards gym use.
If it can take the full weight of a horse standing on it with its small hoofs, then it should have no issues with any weight you might drop on them during lifting.