There are some apps which would work a lot better if you sideload the AndroidTV versions (example windscribe VPN client - night and day between the generic Android and AndroidTV clients).
BUT, some apps (example netflix), will NOT work any better as AndroidTV app with full remote or even available resolutions, unless they are on a box that THEY have approved (including other technical issues like licensing, etc..).
And you mentioned about browser. Keep in mind that Android TV devices do not come with a pre-installed web browser app typically. You can download apps, but you will need to get something that is designed for TV use (maybe something like Puffin TV Browser - optimized for use with a remote). I rarely browse on my boxes so can't recommend anything.
Unfortunately, many people I know will keep a buzz box for iptv use, and then if they use a lot of other apps (like netflix, disney, hulu, etc..), they often have a tiny fire*** device, which is an approved device for many of them.
Also, keep in mind that the B5 is the super entry level device, so it won't be any speed demon for 3rd party apps. At least with device that come with a BT250 remote (like the buzz Classic), the remote is also an air mouse (and uses BT) , which makes using the cursor a "little" less cumbersome, but still far from ideal with the apps that refuse to be TV optimized.