Migration from ominibus to AWS k8s kubernetes - downtime?

HI ,anybody has experience with migration to k8s,
I cant find an answer when and how much downtime is required during migration,
I understand the mother instance need to be offline’ during postgres db migration to k8s, however what about storage objects - lfs, uploads, artifacts, re-configuring mother instance (ominbus packages) from local storage to s3 and running sudo gitlab-rake gitlab:artifacts:migrate will it cause any downtime during migration? we have around 300GB of local objects store data,.
Anybody aware of the facts?
According to migration page https://docs.gitlab.com/charts/installation/migration/index.html, no one mentioning downtime.
Thanks appreciate any tips