Until we finish SERVER-88510, it won't be possible for chaining secondaries to read past the lastApplied opTime. However it would be nice if we can add a backdoor option for engineers to use when they're debugging so that they can see all oplog entries that have been written.

For example, today on a two-node replica set if I stop secondary oplog application through the pauseBatchApplicationBeforeCompletion failpoint, I can continue to insert documents on the primary. However when I try to read oplog entries on the secondary I won't be able to see anything past the lastApplied, which was updated before the pauseBatchApplicationBeforeCompletion failpoint was set.