Subscribe once
It updates itself. That is the only ambitious thing here.
Add the feed to any calendar app. New notes appear on their own every few days and refresh quietly in the background. No account, no app to install, no notifications yelling at you.
https://kashcal.onekash.org/unscheduled-thoughts.icsIn your app
KashCal
Settings → Calendar Feeds (ICS) → Add ICS Calendar. Paste the URL, pick a refresh interval, save.
iPhone
Settings → Calendar → Accounts → Add Subscribed Calendar, then paste the URL.
Google
Other calendars → + → From URL, paste the URL, add.
Outlook
Add calendar → Subscribe from web, paste the URL, add.
Anything else
Look for Subscribe to URL or Add by URL and paste it in.