Re: Just one question
Almost all of them.
That I know of, the only brand issuing regular updates for older phones other than Apple is Xiaomi, who were still issuing quarterly updates to my oldest phone (original Red Rice 3G version) right up to the day my daughter broke the 2nd USB charging port (repaired it once - no spares out there now).
My mums 3 y/o Sony gets about 1 update per year, and performance is as ropey as hell, especially bluetooth connection.
Wifes SamGal Note4 hadnt had an update in several years before she swapped it for a Huawei at Christmas and it was dog slow after the last update it did receive, the Red Rice was faster.
(Old £84 phone much faster than newer £599.99 phone).
My 2 y/o Xiaomi Note 4x gets an update to a built-in app or the OS on average every week.