Recover data with file structure HFS+ on Mojave
This sounds like an ad. It's not. Just timing - I just did this the other day (but on purpose). I've been erasing old drives for the last week or so. For kicks, I reformatted one (If I recall correctly, default security settings (no zeroing or writing random data), formate as HFS+ journaled/encrypted.
Then I decided to see what I could still get from the original drive. 

I used Data Rescue 5. You can download a demo (this is what I used, as my old paid version doesn't work on Mojave). I did not delve in to file contents for more than a few sample files, but I did get what looked like the entire directory structure. The demo let's you recover a whopping total of 10 files. I recovered none, but opened a few for viewing. Paid version is $99. A tad painful, but beats the 2kish that the recovery company was probably going to charge. 

It requires another blank (hfs+) drive to use for working space, and you might want another to recover to.