An implementation of a `NumberTextField` based on `TextField` which should work with any `BinaryInteger` based type.

NumberTextField.swift

import SwiftUI

struct NumberTextField<NumberType: BinaryInteger>: View {

    private let title: LocalizedStringKey
    private let range: ClosedRange<NumberType>?
    private let format: IntegerFormatStyle<NumberType>

    @Binding private var value: NumberType?
    @State private var valueString: String = ""

    private init(
        title: LocalizedStringKey,
        valueBinding: Binding<NumberType?>, range: ClosedRange<NumberType>?,
        format: IntegerFormatStyle<NumberType>
    ) {
        self.title = title
        self.range = range
        self._value = valueBinding
        self.format = format
    }

    var body: some View {
        TextField(title, text: $valueString)
            .onChange(of: valueString) { [valueString] newString in
                if newString == "-" {
                    // do nothing
                //} else if var newValue = NumberType(newString) {
                } else if var newValue = NumberType(exactly: (newString as NSString).integerValue) {
                //} else if var newValue = try? Int(newString, format: format, lenient: true) {
                //} else if var newValue = try? NumberType(newString, format: format, lenient: true) {
                    if let range = range {
                        newValue = min(range.upperBound, max(range.lowerBound, newValue))
                    }
                    value = newValue
                    self.valueToString()
                } else if newString.isEmpty {
                    value = nil
                    self.valueToString()
                } else {
                    self.valueString = valueString
                }
            }
            .onChange(of: value, perform: { newValue in
                self.valueToString()
            })
            .onAppear(perform: valueToString)
    }

    private func valueToString() {
        valueString = value?.formatted(format) ?? ""
    }
}

extension NumberTextField {
    init(_ title: LocalizedStringKey,
         value valueBinding: Binding<NumberType?>, range: ClosedRange<NumberType>? = nil,
         format: IntegerFormatStyle<NumberType> = IntegerFormatStyle(locale: .autoupdatingCurrent)
    ) {
        self.init(title: title, valueBinding: valueBinding, range: range, format: format)
    }

    init(_ title: LocalizedStringKey,
         value valueBinding: Binding<NumberType>, range: ClosedRange<NumberType>? = nil,
         format: IntegerFormatStyle<NumberType> = IntegerFormatStyle(locale: .autoupdatingCurrent)
    ) {
        let wrapperBinding: Binding<NumberType?> = Binding(get: {
            valueBinding.wrappedValue
        }, set: { newValue, _ in
            if let newValue = newValue {
                valueBinding.wrappedValue = newValue
            }
        })

        self.init(title: title, valueBinding: wrapperBinding, range: range, format: format)
    }
}


struct NumberTextField_Previews: PreviewProvider {
    @State static private var value: Int?

    static var previews: some View {
        VStack {
            NumberTextField("Value", value: $value, range: 1...10)
                .frame(maxWidth: 70)
            Text("\(value ?? 0, format: .number)")
        }
        .padding()
    }
}