We’ve done a lot of work with our friends at Deezer over the years, and we’ve integrated their API at least twice.
The current Tidal integration is much deeper than we’ve been able to do with any service in the past, and has required lots of careful collaboration on both sides. It’s been a ton of work, but we think it’s a much better experience than the type of “light” integration we’ve done in the past, and it’s set a higher bar going forward. Hopefully you guys agree 
So, for now we continue to improve our Tidal integration, but we are absolutely open to integrating other services as soon as possible. I’ll let everyone know more as soon as I can, but if you want to see Deezer integrated in Roon, feel free to let them know too 