The request is to have a play next button or option when you search for a song or see a song in one of the "for you" playlists. Below is a use case.
To the point you make on queuing: By default, anything you add to your queue will be added at the end of it. To adjust the order of the items you've added to your queue, hold and drag the "list" icon (on the right of the item's title) and drag it to the desired position.
That is a solution but very inconvenient if you have more than 10 songs in queue. Let's look at the use case: I hear a song from my queue that has 20 other songs queued up. I realize that I want to hear "song xyz" right now. Instead of hitting play next, I have to long-press, tap add it to queue, go to the queue, scroll to the bottom, hold the song and drag it up to the top. I can't be the only person that finds this inconvenient as well as not practical. Apple Music, Amazon Music, YouTube Music all offer the feature, so it must be doable from a technical point of view.