Difference between eject and eas build?

Can eas build handle bare workflows?

I do see modifications on ios and android folders are not considered in eas build.

Can eas build be used for custom react native projects?

Any sample project on config plugins?

Can eas build handle bare workflows?

yes

I do see modifications on ios and android folders are not considered in eas build.

they are, we are uploading a shallow clone of the repo to workers and build it as it is. It won’t work if you are gitignoring android and ios directories

Can eas build be used for custom react native projects?

yes, you will still need to add app.json with slug and owner field, but other than that you should be able to build any react native project,

Any sample project on config plugins?

You can check expo repo for examples how to write plugins (some packages have plugin directory) e.g.

if you just want to use config plugins for libs that already support it, then it should work out of the box when you run expo install some-library Config Plugins - Expo Documentation