Really well structured. The instrumentation and layering is perfect, imo.
As you say, alt/indie-pop, indie-folk. The high plaintive horns makes me think of Badly Drawn Boy.
Definitely has legs to be a complete song. At just over 2 mins, it wouldn’t be unusual for indie-folk, especially if Sufjan is your point of reference. But, you could likely develop it to 3’ – 3’15", if you wanted.
(Gonna find myself saying this a lot, but… It makes for a great demo instrumental, but would benefit from being rebuilt in a more capable DAW.)