I think portainer is probably the best tool for this since you can easily go in and pause/start services as required. Just make sure to go into the containers on portainer and check the restart policy is set to “unless stopped” so you don’t get unwanted restarts after a reboot or anything like that.

I don’t think portainer has any automation options but you could possibly write a short cron script to run docker compose down in the directory of each compose file to shut them down once a month, and pair that with the uptime kuma container to get a notification when your containers are down so you can go into portainer and restart the ones you still need. Though I’ve never had any real issue with running lots of containers at once – there’s 20 on my raspberry pi right now and it’s still got just over a gigabyte of RAM left.