Best way of migrating from Oracle 12.1.0.2 RAC / ASM to Oracle 18 non-RAC ?

Current config is 1 PDB inside a CDB. It's also all hosted in Oracle Cloud Infrastructure if that makes any difference.

I am wondering what my options are for this upgrade scenario with the smallest amount of downtime ?

Export / Import is always an option but probably 5-6 hours in that by the time the export completes and import does its thing and indexes rebuild.

If I was going from 12 to 12 on non-ASM in the past I've turned on backup mode, copied datafiles over to the new server, run a CREATE CONTROLFILE and then applied archive logs periodically during the day up to the point of shutdown of the source and had the whole thing copied over in 15 minutes or less.

I'm not quite sure what my options are in that respect when running ASM (and also every time I've done that in the past it's been a non-Container database so I'm a little unsure how a CDB/PDB adds complications to that).

The business is prepared for a 5-6 hour outage one Saturday night if needed, but I figured I'd pick the brains of some smart people here to see what other options might be available.

Thanks
Steve

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