June 4, 2020
The same person (thanks, Dave!) found a similar system, called PushOver, supporting all systems. While PushBullet was totally free, PushOver requires a one-time payment, but of just 5 USD after the trial period.
In any event, we've added support for PushOver, both from the Dragonfly macros (already active) and from the Solo (safe / unsafe notifications) - will be included in next release due, hopefully, tomorrow.
To "activate" PushOver, just specify a key (token) starting with "po-" (3 letters and a hyphen).
The software will still mention "PushBullet key", etc, that will change in future versions, but just adding those 3 letters before the actual key/token will result in a PushOver message being sent, instead of a PushBullet one.
Hope this helps.