Cloud platform specific stuff is way easier to learn compared to the core concepts.
Personally I’ve been using oracle as a test bed for that given their generous free tier but for production I’d probably use GCP
I say that as a person who is not super bullish on big cloud architectures. So, also learn a more 'imperative' tool like ansible (even with its sucky syntax), for repeatably provisioning hosts.
Orgs that don't use tools like that are, in my opinion, strictly of a lower level of maturity and having-shit-together-ness than ones that do.
Once you know how to provision the resource and all the switches and dials on it, you can then go find out what they do and how they work by readying the cloud platforms docs.
This MO works pretty well for me.
Also avoid to waste your life learning proprietary technology that will become obsolete and discontinued. Software containers are likely there to stay, the latest serverless framework from a cloud provider will likely not.
Containers can be hosted on a 100% open source software platform, which is quite a nice feature indeed. Unlike Heroku, Lambda, SQS, Aurora, etc etc.
As a person, who played quite a bit with Digital Ocean and would have loved to skip the server setuping, I think it would be perfect for my future projects as well.
Personally I stay away from Azure, IMHO it just seems clunky. (Just my personal opinion so take it with a grain of salt.)
BTW, if you’re new to cloud stuff this resource might come handy: https://cloudresumechallenge.dev/
Best of luck!
Start there