Congrats on getting everything working - it looks great!
One piece of (unprovoked, potentially unwanted) advice is to setup SSL. I know you’re running your services behind Wireguard so there isn’t too much of a security concern running your services on HTTP. However, as the number of your services or users (family, friends, etc.) increases, you’re more likely to run into issues with services not running on HTTPS.
The creation and renewal of SSL certificates can be done for free (assuming you have a domain name already) and automatically with certain reverse proxy services like NGINXProxyManager or Traefik, which can both be run in Docker. If you set everything up with a wildcard certificate via DNS challenge, you can still keep the services you run hidden from people scanning DNS records on your domain (ie people won’t know that an SSL certificate was issued for immich.your.domain). How you set up the DNS challenge will vary by the DNS provider and reverse proxy service, but the only additional thing that you will likely need to set up a wildcard challenge, regardless of which services you use, is an email address (again, assuming you have a domain name).
If you know your VPN’s DNS server, you can change your local DNS so that it redirects your specified domains/subdomains to the appropriate, local IP address and all other requests would then use your VPN’s DNS.
If you don’t know your VPN provider’s DNS server information, you may be able to still do something similar to the above depending on your setup. Otherwise, you could run your own DNS resolver or use a different DNS provider. I guess doing so could potentially be used to further fingerprint you, but the concern about “DNS fingerprinting” is moreso DNS leaks where your DNS queries are accessible to unintended parties due to improper configuration.
I believe the only other option would be to change your hosts file on each device you want to use to connect to your services, which is probably not the best approach and may be challenging/impossible for certain devices.
Also, unless you setup the self signed certs to be trusted on a network/domain level (or again on each individual device), you will likely get a warning/error about the self signed certs when accessing your services. You may need to work through this process each time the certs renew.
I recommend buying a domain if you do not already have one and finding a service that provides wildcard certification challenges. This would allow you to setup a valid, trusted certificate that you could reuse for all of your services. The only thing that you would need to provide is an email address (can be any email address) and your domain name (in addition to other information that may be required to setup an account at the cert provider, but you may already have an account there as it could be the domain name registrar or other services like VPS providers, Cloudflare, etc.). Since it is a wildcard cert, each subdomain does not need to be set publicly and if you only use the domain within your network, the domain does not need to be publicly associated with any IP address.
If you do go forward with that approach, you could use the wildcard cert directly within NginxProxyManager or other reverse proxies. They will also automatically update/maintain the cert for you.