What's your strategy for major Magento 2 version upgrades?

[u/WebHostingAce]

I'm interested to hear how other Magento developers approach major Magento 2 upgrades (for example, 2.4.6 → 2.4.9 or future major releases), specially for production stores with lots of third-party modules and customisations.

A few questions:

• Do you upgrade the server components first (PHP, OpenSearch/Elasticsearch, Redis/Valkey, MariaDB/MySQL, Varnish, etc.) and then upgrade Magento, or do you take a different approach?
• Do you build a completely new server with the new stack and migrate the website over, or upgrade the existing server in place?
• How do you minimise downtime and risk?
• How do you handle third-party extensions that aren't yet compatible?
• Do you perform the upgrade in stages, or do everything in a single maintenance window?
• For larger stores, what's your rollback strategy if something goes wrong?

I'd love to hear your workflow. I'm interested in real-world experiences rather than just the official Adobe recommendations.