Fast switchover

Hello all the readers,

For some projects we need a fast manual switchover to address Near Zero downtime maintenance
(not speaking here about automated failover like those provided by HA tools, but just planned, controlled operations)

Database Physical replication switchover itself:
- initial replication (before switchover) should be synchronous or replication LAG should be controlled to prevent data loss.
- Switchover duration seems not "compressible" under a few seconds (because of primary shutdown, promotion, new standby catch up, ...)
- Application retry strategy (after disconnection) should be tuned using proper retry delay. Pooler or specific driver may help.

May logical replication ( bi-directional, with one instance RW and the other RO) be a better solution ?
This solution is more complex because of sequences, DDL, Large Objects, Conflict resolution (if any)
but switchover should be faster ...

what could we expect (in term of downtime in both worlds) ?
Are there any Logical Replication Manager available, or admin tools (preferably open source) ?
any feedback is welcome

Thanks in advance
Regards
PAscal