Successfully figured it out! Decided to switch over to using crypto-js library and that did the trick.

import moment from 'moment'
import crypto from 'crypto-js'
import axios, { CancelToken } from "axios"   
    
async function send() {         
    const access_key = "XXXX"
    const secret_key = "XXXX"
    const method = 'POST';
    const service = 'execute-api';
    const host = 'dfadfadfdafda.execute-api.us-east-2.amazonaws.com';
    const region = 'us-east-2';
    const base = "https://"
    const content_type = 'application/json';

    // DynamoDB requires an x-amz-target header that has this format:
    //     DynamoDB_<API version>.<operationName>
    const amz_target = '';

    function getSignatureKey(key, dateStamp, regionName, serviceName) {
        var kDate = crypto.HmacSHA256(dateStamp, "AWS4" + key);
        var kRegion = crypto.HmacSHA256(regionName, kDate);
        var kService = crypto.HmacSHA256(serviceName, kRegion);
        var kSigning = crypto.HmacSHA256("aws4_request", kService);
        return kSigning;
    }

    // ************* TASK 1: CREATE A CANONICAL REQUEST *************
    // http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html

    // Step 1 is to define the verb (GET, POST, etc.)--already done.

    // Step 2: Create canonical URI--the part of the URI from domain to query 
    // string (use '/' if no path)
    // Create a date for headers and the credential string
    const amz_date = moment().utc().format("yyyyMMDDTHHmmss\\Z")
    const date_stamp =  moment().utc().format("yyyyMMDD")

    //// Step 3: Create the canonical query string. In this example, request
    // parameters are passed in the body of the request and the query string
    // is blank.
    const canonical_querystring = ''

    //## DOing step 6 first so that I can include the payload hash in the cannonical header, per https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html
    // Step 6: Create payload hash. In this example, the payload (body of
    // the request) contains the request parameters.
    //const payload_hash = hashlib.sha256(request_parameters.encode('utf-8')).hexdigest()
    const payload_hash = crypto.SHA256(request_parameters);

    // Step 4: Create the canonical headers. Header names must be trimmed
    // and lowercase, and sorted in code point order from low to high.
    // Note that there is a trailing \n.
    const canonical_headers = 'host:' + host + '\n' + 'x-amz-content-sha256:' + payload_hash + '\n' + 'x-amz-date:' + amz_date + '\n'
    
    // Step 5: Create the list of signed headers. This lists the headers
    // in the canonical_headers list, delimited with ";" and in alpha order.
    // Note: The request can include any headers; canonical_headers and
    // signed_headers include those that you want to be included in the
    // hash of the request. "Host" and "x-amz-date" are always required.
    const signed_headers = 'host;x-amz-content-sha256;x-amz-date'

    // Step 7: Combine elements to create canonical request
    const canonical_request = method + '\n' + canonical_uri + '\n' + canonical_querystring + '\n' + canonical_headers + '\n' + signed_headers + '\n' + payload_hash

    // ************* TASK 2: CREATE THE STRING TO SIGN*************
    // Match the algorithm to the hashing algorithm you use, either SHA-1 or
    // SHA-256 (recommended)
    const algorithm = 'AWS4-HMAC-SHA256'
    const credential_scope = date_stamp + '/' + region + '/' + service + '/' + 'aws4_request'
    const string_to_sign = algorithm + '\n' +  amz_date + '\n' +  credential_scope + '\n' +  crypto.SHA256(canonical_request);

    // ************* TASK 3: CALCULATE THE SIGNATURE *************
    // Create the signing key using the function defined above.
    const signing_key = getSignatureKey(secret_key, date_stamp, region, service)

    // Sign the string_to_sign using the signing_key
    const signature = crypto.HmacSHA256(string_to_sign, signing_key);
    // ************* TASK 4: ADD SIGNING INFORMATION TO THE REQUEST *************
    // Put the signature information in a header named Authorization.
    const authorization_header = algorithm + ' ' + 'Credential=' + access_key + '/' + credential_scope + ', ' +  'SignedHeaders=' + signed_headers + ', ' + 'Signature=' + signature

    // For DynamoDB, the request can include any headers, but MUST include "host", "x-amz-date",
    // "x-amz-target", "content-type", and "Authorization". Except for the authorization
    // header, the headers must be included in the canonical_headers and signed_headers values, as
    // noted earlier. Order here is not significant.
    const headers = {
        'X-Amz-Content-Sha256':payload_hash, 
        'X-Amz-Date':amz_date,
        //'X-Amz-Target':amz_target,
        'Authorization':authorization_header,
        'Content-Type':content_type
    }

    // ************* SEND THE REQUEST *************
    var response = await axios({
        method: method,
        baseURL: base + host, 
        url: canonical_uri,
        data:request_parameters,
        headers: headers,
    });
    console.log(response)
}