I've not had much trouble with Xcode in the past 15+ years I've been using it. Its biggest warts involve Interface Builder, which is easily avoidable by using code for UI instead of XIBs or storyboards.
With Android Studio, I'd say the ways that it being an IntelliJ IDE puts it above Xcode are cancelled out by other aspects of Android development, which can be abysmal. Swift Package Manager and Clang/llvm code stripping have never made me want to tear my hair out the way that Gradle and Proguard have for example.
I've never seen a build system that makes sense, aside from make which is more for individual binaries. If the higher layer build system were just some Python scripts I can look at and understand, that'd be neat.
This depends entirely on how well the thing you're using bothered to support multiple platforms.
Browsers are pretty much the gold standard here, ironically. You might have to care if it's Firefox or Chrome but it's very rare for you to have to care if it's Firefox on Windows or Mac or Linux. It's exactly why React is simultaneously horrible and everywhere.
So it can be done, it's just a question of whether that framework has done it well, ideally while also doing other things well (unlike React).
How miserable it would be trying to write Java or kotlin targeting iOS apps. I think this will be the same.
Just use the native tools and languages for the platform. Swift/Objc/xcode for iOS. Java/Kotlin/Android Studio for Android.
You will be so much happier.