This simple script fetches hackerone.com (for example) subdomains from https://www.shodan.io/domain/hackerone.com
git clone https://github.com/seqrity/shodan_subdomain.git && cd shodan_subdomain
apt install python3-pip
pip3 install -r requirements.txt
python3 shodan.py hackerone.com
There is limitation on shodan base on IP. If you don't receive subdomains might Shodan blocks your IP and should change your IP.