Interchangeability between atop and on top of

Atop seems to be used interchangeably with on top of when in sentences such as atop(/on top of) a mountain, as a preposition. However, is it correct if I use it to replace on top of in the sentence below?

This provides greater utility, on top of comfort.

I would greatly appreciate a detailed answer, thank you so much in advance!

You should not say

This provides greater utility, atop of comfort.

because atop means physically on the top of, whereas your intended meaning is something like "in addition to".

The entry in Lexico says

atop
PREPOSITION
literary

On the top of.
the weathervane is perched atop the Great Tower

atop
ADVERB
literary

On the top.
the air-raid siren atop of the County Courthouse

The indication literary means that the word isn't used much in spoken English.