I have a Magento 1.9 store running on Debian 9.13. I know Debian 9 will reach the End of Life in June 2022. If I don't update both Debian and Magento, could be they run "forever"?
What should I do? I'm developing my Magento 2 store but in the meanwhile...
It still runs but there will be no further updates or upgrades. You should upgrade your website to Magento 2. In the Magento version, there will be many updates and especially it supports more features than Magento 1.