metallb sounds like what you need, basicall you give it a range in your subnet (excluded from dhcp/Router!) and it assigns those ips to your loadbalancer services, it broadcasts this IP over Arp or bgp which makes automatic failover work.
When making an application instead of coding for one platform you have to code for 5 and also convince Apple and Google to accept your app (Nextcloud is really feeling this one).
Meanwhile HTML + JavaScript works on most smart fridges.
Is there a self hosted version of it/something like it?