Gave the Symfony 7.3.0-BETA2 a go and think there will need to be a few changes made to keep this working. But, it's still not 100% actionable since there is still a chance of change.

Think some underlying types have changed in Symfony - e.g. from changes in symfony/symfony#60389

PHP Fatal error:  Declaration of Wrep\Daemonizable\Command\EndlessCommand::handleSignal(int $signal): void must be compatible with Symfony\Component\Console\Command\Command::handleSignal(int $signal, int|false $previousExitCode = 0): int|false in /home/pieter/development/daemonizable-command/src/Wrep/Daemonizable/Command/EndlessCommand.php on line 81

Don't expect this library to be working with the beta of an unreleased version, but might be one to run in CI, e.g. setup a monthly travis cron with the latest tagged release of symfony, see a failure, get a pre-release ready, release it when the latest version is cut?