Am I to make an A record with my domain and point it to my public IP? Then enable Cloudflare proxy service. Then a CNAME record would be the subdomain to whatever service I want and then setup properly in nginx proxy?
That would work just fine. As long as you have the records in Cloudflare DNS and the domain is all set to proxy something in NPM you're good to go. And yes, using a CNAME from the subdomain to your A record is the most elegant way so you only have to update that one IP address as your IP changes.
If I don’t have a static IP from my ISP is there a way to automatically update my dynamic IP in Cloudflare so I don’t loose access?
It's a simple API call, or there's lots of 'my-first-script' style project for this on github.
To throw something out from leftfield though... if you're going to be using Cloudflare to proxy all your (sub)domains, then if you have a dynamic IP you will be better off using a Cloudflare Tunnel (cloudflared) to get online. Doing so solves both the issue of creating your own CNAMEs and updating your dynamic IP record - you simply don't ever do either as Cloudflare will take care of all the record creation and routing of traffic for you. GL.
You can either point the Cloudflare Tunnel directly to the backend, or point it to the service on NPM and keep that in place proxying to the backends.
Whilst the latter seems to duplicate functionality, it does allow you (down the track?) to have local access use the same hostname as public access by defining local DNS entries for
subdomain.example.comwhich point to the NPM IP address (instead of resolving to Cloudflare's IP address when looked up on public DNS servers).I would think most homelabber/self-hosters end up with that topology as opposed to having everything have to go through Cloudflare even when its purely local access at home.