Yes — this is actually one of the main use cases of KeepMyNumber.
The app lets you receive calls via internet (Wi-Fi or mobile data), regardless of which SIM is providing that data.
That means you can:
Use a local SIM or eSIM for cheaper data or local calling abroad.
And at the same time, stay reachable on your original number through KeepMyNumber.
This setup is common for:
Travelers who want to avoid roaming charges.
Expats or remote workers who need dual-number functionality.
Your mobile data (from any SIM) just needs to be active so that the app can receive VoIP calls.