This script prints out the current list of Amazon2 Linux AMI's by region (kernel 5.10, HVM, x86_64, gp2). Changing the image variable and the Path filter make this capable of searching for any public/shared image.

amazon2-linux-amis-for-cloudformation.py

import boto3
from json import dumps
from yaml import dump

image = 'amzn2-ami-kernel-5.10-hvm-x86_64-gp2'

regions = [
    'ap-northeast-1',
    'ap-northeast-2',
    'ap-northeast-3',
    'ap-south-1',
    'ap-southeast-1',
    'ap-southeast-2',
    'ca-central-1',
    'eu-central-1',
    'eu-north-1',
    'eu-west-1',
    'eu-west-2',
    'eu-west-3',
    'sa-east-1',
    'us-east-1',
    'us-east-2',
    'us-west-1',
    'us-west-2',
]

amis = {}
for region in regions:
    client = boto3.client('ssm', region)

    paginator = client.get_paginator('get_parameters_by_path')
    iterator = paginator.paginate(
        Path='/aws/service/ami-amazon-linux-latest'
    )
    matches = []
    for batch in iterator:
        matches.extend(list(filter(lambda det: image in det['Name'], batch['Parameters'])))

    if len(matches) < 1:
        print('no matches found in', region)
        continue
    elif len(matches) > 1:
        print('multiple matches found in', region, '- perhaps you should narrow your results')
        for match in matches:
            print("\t-", match)

    # grab the first one if we have more than one
    print('found', matches[0]['Name'], matches[0]['Value'], 'in', region)
    amis[region] = {'AMI': matches[0]['Value']}

print(dumps(amis, indent=4))
print(dump(amis))