Streaming is a great way to discover new music and many of us have exchanged links in the What Are You Listening to threads. Mostly Youtube links because the videos are fun too. I have Premium to avoid the ads and with YT Premium you can get slightly better audio available on their music service. Outside of YouTube I probably would have gone with Tidal (I don't like Spotify's revenue model).
Roon is more for playing your own digital library but also supports streaming for services like Tidal or Qobuz. For digital libraries I think Roon is the best service but expensive. I finally gave in and got a lifetime membership to avoid the annual fee. I would NOT get Roon for just streaming. If you just want access to Tidal / Qobuz / Spotify / Prime or Apple Music then I would get a WiiM. It has very good streaming support at a reasonable cost (there are some crazy expensive streamers out there).
If you want YouTube or other video services on your TV and 2-channel system, then I would look into an NVidia Shield TV Pro or a small form factor PC for internet access. The Shield is several years old now but still supports all of the major video and music streaming services. I use it mostly for YouTube, Netflix, Disney and my personal digital library. It's easy to set up as well.
A mini personal computer, like one from Beelink, can give access to a little more content since you can use a web browser (browsing the web on the Shield is not a good experience). You can use a wireless keyboard and trackpad or mouse and have access to anything on the internet that is web based. There is a little more setup involved but that's were kids and grandkids come in handy.
So think about how you want access to services. Some receivers have streaming support so all you need is the phone app or a tablet. Don't like using a phone, then the Shield has a nice remote and works through the TV. Same with the PC but with a bulkier keyboard (there are mini keyboard options too).
With the size of your CD collection that may never become an issue though.
