A Phone from 2014 is really really old... I feel for your wife.
I have no problems with IoT devices, and online services. As long as used in a smart way. Honestly for IoT Devices, use more advanced networking hardware. I'm all for home automation and smart devices, but they all are on private networks separated out with vlans and kept in line with firewall rules. They only do what is needed, and many private networks are key here. My Camera network doesn't even touch the outside world, but my DVR software allows me to remote view from anywhere.
I'm a heavy user of two factor auth, and really this is the biggest factor in keeping you safe. Not using Multifactor is the biggest flaw in peoples idea of being secure. I don't care if your password is complex.
While I do like Nextcloud, be careful with it. This is not something you should really trust you data with unless you have a pretty beefy setup under it. Like a Pretty well configured Freenas setup or something. Data rot is a real thing, and HDD failures are a real thing. Cloud backups are a thing for a reason, and Onedrive is a cheap way to make sure photos will live on. I can't stress this enough, as i've seen people loose everything from not knowing how to configure a proper data store.
As someone that isn't a fan on jank, used a computer on a TV is something I would have done years ago when I was in school and broke. But I paid for 4K and 7.2 surround and you are not going to get that via the web browser