Hello, new here. Once a device is set up in HA, does its original app (eg Tuya, Smartlife, etc) become redundant? If I uninstall the original app does HA even care? I know the integration needs to stay in HA, but what about my phone app, could I in theory delete the Tuya app and just keep the account open?
Also once a device is setup in HA, does the integration matter? HA has the connection info doesn’t it?
An older fella trying to understand all this.
Thanks
Tuya is not a good example as it tends to need access to the Tuya services to work. Some older stuff can be local only, maybe even newer stuff from tuya but as I don’t use it I can’t be sure.
Some stuff can be run without an app installed like Shelly and probably a lot of other stuff. So be careful what you buy if you want it to be local only. Check the integrations docs for info on what you want to use.
Integrations are needed for all devices it is the way they communicate with HA.
Read the docs before committing to HA.
Try it out before you buy any kit, HA is easy to run as vm on any PC. It can be a bit of a learning curve and is not for everyone.
That being said we are all very helpful and if you ask a good question most will go out of their way to help, we all remember where we started, and the help we needed .
And as a general advice, avoid Tuya devices if you can for newer ones 
Tuya zigbee stuff is fine and local only.
And if I was starting out now I would be mostly Zigbee and esphome stuff.
Does the app need to stay. Depends on the app but usually yes. Not for day to day but you may need it for maintenance. I just put them all in a folder on my phone that’s not on the home screen. If they’re needed I have them…
Once the device is setup. The integration is PARAMOUNT. it’s HOW HA connects you kill the integration. Poof.
I’m with @NathanCu on this one:
All my ‘Smart Home Apps’ sit in a folder and some, e.g. Shelly, I haven’t touched for a year, while I need to check with others now and then - either because the integration doesn’t provide the same functionality, e.g. Govee, or because the device drops off of Home Assistant and I need to find out, if e.g. for VeSync, it’s a device issue or if it’s a (cloud) service issue.
This would be resolved, if all my devices were local-only, but when I bought some of them, there was no Zigbee version - so, for now, I’ll have to deal with it that way because I don’t have the budget to replae them 