Answer
Yes. Third-party maintenance (TPM) providers take over break-fix service and parts sourcing for hardware IBM no longer services directly through standard support. A TPM contract does not restore IBM firmware development, but it does provide continuity, predictable support costs, and time to plan a migration on your own schedule rather than a forced one.
For a Power9 shop past End of Standard Service, TPM is usually the fastest way to close the support gap without committing to an immediate hardware purchase.