There is, Termius works with the Redpqrk serial adapter, however it terminates with a RJ-45 plug that’s wired according to Cisco Specs. https://redpark.com/usb-c-console-cable/
Redpark SDK is public, perhaps serial console support can be added to an open-source terminal app, https://redpark.com/developer-tools/
Weird Apple restriction on DB-9 vs RJ-45 interfaces:
Per current Apple MFI policy — apps developed for the Serial Cable or Serial + Power Adapter may be used in private deployments or deployed via Apple Business Manager or Apple School Manager. However apps may not be deployed via the public Apple App Store.
Apps developed for the Console Cables or DEX Cables may be deployed via a public Apple App Store if desired.