Migrating g-code fiiles across printer manufacturers

i will take delivery of my new Creality K1 Max tomorrow (scheduled then at least);
i have many g-code files from my old flsun v400 (cura and prusa sliced);
i know it would be stupid to just blindly use them cold on the new printer;
i dont know what g-code flavor creality uses and since their code is closed i assume only their own slicer is the intended source;
i did however see a youtube video where a seasoned 3d printing pro used a prusa sliced g-code file and modified it for use on the creality and it worked ok;
i think/recall what they did was use the creality slicer and copy the start and end print sections and substitute those sections in the prusa-generated code;
does any of that make sense ?
this youtube video pretty much bashed the creality slicer in favor of the prusa; they demonstrated a simple print using both and the creality product was very noticeably worse BEFORE the mods to the start and end print sections;
maybe my core question lies in printer profiles, is it as simple as changing the bed size + Z and the various g-code flavors all become basically the same ?

I use the creality print slicer for this machine. I know there are setting available for Cura and Prusa Slicer but have not tried them. Creality slicer seems ok and have not had issues with it, just getting used to information that you need to look for.

I don’t use it. Creality seems to be a clone of cura with some variations. No it is unlikely that a bed size change will work well it will likely need other modifications too. I would assume you will either need to develop your own or find one someone else has figured out and mod it to your needs.

I have had success with both creality slicer and cura with the k1 max. I have the creality “open source” firmware version. Creality slicer works well and lets you print from the slicer over the network. You can’t do that from cura or prusa unless you have the jailbreal firmware and have setup moonraker. As far as the start g-code, just copy from creality slicer to your preferred slicer. The start and end g-code are very minimal as most of what the machine is doing is controlled by macros. You can also duplicate the speed, accelleration, retraction etc from the creality slicer profiles.

the g-code files are simple text files, i suppose to satisfy my own curiosities, i will have to use a good text compare utility and see the differences and try to interpret them into physical end-product