Since these devices are long out of production and official Nokia support servers are offline, you must rely on community-maintained archives. Internet Archive (Wayback Machine)
Even with the correct "s60v1 rom download," you will hit snags. s60v1 rom download
often host collections of old firmware and software uploaded by preservationists. Specialized Forums : Communities like All About Symbian Since these devices are long out of production
To find the right download, you must identify the specific model, as firmware is not interchangeable between different hardware. Specialized Forums : Communities like All About Symbian
Since these are legacy proprietary files, they are mostly found in community archives and emulator resources:
First, I should confirm which devices use S60v1. Let me list them. I think the original Nokia N-Gage, 6610, 7650, 3650. Each of these would have their own firmware. So the user would need to know their specific model and then find the correct ROM for it.
Most accurate emulation today is achieved using from Symbian OS v6.1 SDK with custom patches.