Want to improve my home automation for offline use, create new setup

I currently have my home automation setup using Alexa Smart speakers but want to improve everything and also the ability to use in the case of an Internet outage. Not wanting high end due to budget, any hardware needs to be available UK.

My current environment consists of:
4 x Alexa Echo Dots
Eufy Video Doorbell + Indoor cam (doorbell uses the smart speakers as chimes)
Govee tv backlights + various strip leds.
Multiple plugs, most run on smartlife, tapo, Ener-j etc.
Electric curtains.
Floor uplighter
Washing machine (HON App)
Denon avr (HEOS App)
LG OLED
Nvidia Shield Pro 2019
Homatics box r 4k plus
Xbox Series X
Wall switch, if replaced, needs to be no neutral, 1-gang, 2-way, capacitor installed at light fitting.

I have access to: Spare Android tablet, PC, not sure best route hardware wise going forward. Alexa integration is important I guess.

Currently use the following skills
Eufy
HEOS
Tapo
Enerj
Govee
HON
LG ThinQ
Smart Life
Sky News
Bbc news

Hello djpleasure,
Welcome to the Home Assistant Software Forum!

That is a nice list of stuff, but your actual question is not clear.
Maybe read this over again and try to let us know that you want to do. Are you having problems installing Home Assistant? Are you wondering if HA will fit your needs?
Many of the things you list will work fine in HA.
Since this is the Home Assistant Software Forum, I’m assuming your question is somewhat related to this software, but the actual goal is unclear.
https://community.home-assistant.io/t/how-to-help-us-help-you-or-how-to-ask-a-good-question/

Your first step is to take your internet down and see what stays working… if its working then leave it, if it breaks then look for offline replacements.

Case in point anything Alexa (will just spit out garbled gibberish when you try to use it without internet or Apple based will require the internet connection to work (you can still do manual control of functions via an apple device)

This video shows you an example of what to test for.

as well as this one:

As for hardware to get setup using HA I would suggest the yellow as your jumping off point if you don’t already have a system you can dedicate to either a direct or virtual install to play with to get used to it and to see what integrations for your current hardware is supported either in the main addon’s list or via the HACS list.

You will also need to make sure you have the right adapter based on the hardware that is supported and the route you take with the install. i.e you will need a zigbee or z-wave one for those protocols, a thread border router for matter over thread and anything else will just be using wifi.

  • Start here.
    - Look up each of your devices by manufacturer (eg. Amazon Alexa).
    - At the very top right, you will see that Integration’s [IoT class] (Classifying the Internet of Things - Home Assistant). EDIT: since I wrote this post 3 days ago, the integrations page gives you an option to immediately filter by IOT class, which makes things much simpler.
  • Anything which mentions Cloud (Cloud Push or Cloud Polling) will not work without an internet connection.

I can tell you right now that Alexa & Xbox won’t work, but LG & Denon will. SmartLife crap stuff will not work without internet via Tuya, but can be made to work locally using custom integrations like TuyaLocal or LocalTuya