I was wondering if I could store my finished home brew in a fermenting bucket that has a spout on the side. Of course not the same one it was fermented in but a clean one. Will it hold its carbonation? Was thinking might be simalor to a 2 l. pop bottle?
A bucket generally would have a whole lot of trouble holding carbonation. Especially once you started drinking. Without a constant stream CO2 you would lose your carbonation to the headspace in the vessel. My opinion, trying to carb in a bucket is a waste.
When you say "finished home brew" you'll need to expand on finished.
Generally speaking, using a secondary fermenter in the long term is fine, so you'd move to a secondary vessel and ensure the airlock is maintained with sanitized fluid.
You carbonate (normally) in kegs or bottles, if the concern is that you don't have enough bottles, don't prime in your secondary, but wait until you have a suitable pressurized vessel (kegs, or bottles) to carbonate in.
Source: I have batches in secondary for months, a mead for about a year, and lambics normally take a year or more to allow the flavours to merge.