The Sigma fp/fpL has no IBIS neither. No Sigma fp user seems to complain about it. If you need IBIS, buy a different camera like a Ricoh GR3 or Lumix S9. There is no camera for everybody. Each camera has pro and cons. You have to find the best compromise for your own use cases.
I love Lumix IBIS, but I do not think, that I really need it that much in most situations. Especially not with 24MP. You can adjust shutterspeed and handshake is no issue anymore. Like in the last 40 years of photography. Todays modern sensors give us excellent image quality even at high ISO. So that argument does not count neither.
If you shoot a moving subject, IBIS does not help at all. IBIS is not a solution for everybody. Neither IBIS, nor an EVF is the holy grail.
Think about your use cases and then pick the right tool with the right features for the task.
I love Lumix IBIS, but I do not think, that I really need it that much in most situations. Especially not with 24MP. You can adjust shutterspeed and handshake is no issue anymore. Like in the last 40 years of photography. Todays modern sensors give us excellent image quality even at high ISO. So that argument does not count neither.
If you shoot a moving subject, IBIS does not help at all. IBIS is not a solution for everybody. Neither IBIS, nor an EVF is the holy grail.
Think about your use cases and then pick the right tool with the right features for the task.