What programming language(s) do both iOS and Android support?

I want to make a mobile app, but I am very new to the field. I am looking for what language I should go for. I know that iOS supports Swift and Objective-C. Android supports a range of languages, but Kotlin or Java are best. However, it seems that C# is supported on both iOS and Android (but I can't find a solid statement). I am also open to (free) converters. In terms of the app, I have these requirements:

• Make HTTP/HTTPS requests
• Text rendering
• Basic Audio Capabilities
• Image Rendering
• Buttons (optional)

What would be the optimal language? I don't want an opinion as much as I want a simple list. If there is no such language that supports both systems, what would be the easiest two languages to port between? Thanks in advance!

Generally speaking, there are 3 popular options, with widespread use and community support:

1. Flutter framework (uses Dart)
2. React Native (uses JS)
3. Kotlin Multiplatform (business logic in Kotlin, UI can be drawn natively for the platform)

If you're still not satisfied with these frameworks, other options would be:

1. Xamarin (uses .NET/C#)
2. Ionic (uses JS)