Is there any one (or more) NON-battleship(s) that have guns as large as (or larger than) any one battleship)?
Monitors count. These are smaller, much less armored ships, with very large guns. Used for shore bombardment. See, e.g, HMS Abercrombie. https://en.wikipedia.org/wiki/HMS_Abercrombie_(F109)
Well, yes, some battle cruisers had battleship sized guns, esp during WW1.
The HMS Furious had 18" guns, which proved impractical, but were bigger than the battleship guns of the day.
Then there are monitors, not the Civil war ones, but later, like the https://en.wikipedia.org/wiki/HMS_General_Wolfe_(1915) with a 18" gun,
the US navy had some also:
Several other navies had coast defense ships with 12’ guns.
The Lord Clive-class monitors in WW1 were particularly heavily armed, with an 18 inch gun firing a shell larger than those later used by the IJN Yamato-class battleships, at over a ton and a half shell weight. https://en.wikipedia.org/wiki/BL_18_inch_Mk_I_naval_gun [EDIT, as mentioned by DrDeth, just above.]
The wiki for the Lord Clives notes (albeit with “citation needed”) that their use at the end of WW1 against a railway bridge is the longest range that a British warship has ever fired on a wartime target with a gun., at 36,000 yards. https://en.wikipedia.org/wiki/Lord_Clive-class_monitor
Although the guns in question were NOT bigger than battleship guns, the French submarine Surcouf sported atypically large guns.