Inscribe.  

 https://wetransfer.com/upload 

 https://filebin.net/ 

 Zapstr.live 

 Actually maybe this just uses nostr.build. 

 Nostr.build unless more than 25MB.
Audio only file should be .mp3 

 It's actually .m4a 

 On that note, for others reference:
Zamzar.com is an easy way to convert files 

https://www.zamzar.com/convert/mp4-to-mp3/ 

 It's m4a 

 Oh, well zamar can do that too:

https://www.zamzar.com/convert/m4a-to-mp3/ 

 We should support it 

 Setting up your own personal s3 bucket is certainly a pain in the ass initially, but it’s such a nice thing to have. You have virtually unlimited storage and are paying pennies