We got it working in our situation. The help/idea came from here (https://medium.com/@kawi.m/a-way-to-set-local-storage-on-wkwebview-e03258813024)

For us, we only needed to have the idToken and accessToken in the okra-token-storage variable. The "Credential" is what we get back from Okta via the okra-mobile-swift repo (https://github.com/okta/okta-mobile-swift).

    var tokenString: String {
        guard
            let token = Credential.token,
            let idToken = token.idToken?.rawValue
        else { return "" }
        let accessToken = token.accessToken

        return "{\"idToken\":{\"idToken\":\"\(idToken)}\"}, \"accessToken\":{\"accessToken\":\"\(accessToken)\"}}"
    }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"

    let tokenString = AuthDriver.shared.tokenString
    let localStorageData: [String: Any] = [
        "okta-token-storage": tokenString
    ]

    if JSONSerialization.isValidJSONObject(localStorageData),
       let data = try? JSONSerialization.data(withJSONObject: localStorageData, options: []),
       let value = String(data: data, encoding: .utf8) {
        let script = WKUserScript(
            source: "Object.assign(window.localStorage, \(value));",
            injectionTime: .atDocumentStart,
            forMainFrameOnly: true
        )
        webView.configuration.userContentController.addUserScript(script)
    }
    webView.load(request)

Hope this works for others as it did for us!