Most cloud providers have some kind of firewall that allows to configure a resource being accessible only from certain IP addresses. Worth it to set to your home IP address, as long as it’s static.

Tbh there also was iPod Touch, which did everything iPhone did except making calls.

Okay, I guess I just need to buy a different one, luckily they are cheap.

Out of recommendations given here I’d ignore Arch/Manjaro, for a server you want something that you can set up and forget about and not explode when you try to update the packages after not doing so for 3 months.
Kubernetes and the likes are a bit of an overkill unless you’re planning to expand to having multiple machines or want a learning experience.
I’d recommend docker compose or podman, you generally don’t want bare bones docker as running your containers via docker run sucks ass.

How often does your temp/humidity sensor report? I’ve also got a Tuya one from Aliexpress and had to shelve it because it was spamming the sensor data 5 times a second.