RULE #1 ! NEVER BUY ANYTHING TILL YOU HAVE A PLAN !!!
Sounds like everything you intend to run is 120V. I strongly suggest you get yourself a Kill-A-Watt meter you can plug our devices into to measure how many amps/watts you are pulling. See here:
https://www.p3international.com/products/p4400.html Then add up the the power used to give you an idea of what you "need" then add 20% cause everyone is always short.
A High Frequency Inverter/Charger is perfectly suitable for electronics like computers etc, they will handle fridges & freezers (with a bit of effort) and that's good as it can save you some bucks. NOTE that if you are NOT going to have Solar Panels, there is little point in getting an AIO with Solar Controller(s). You will want the ability to use the 120V Wall plug to be able to provide Charging Capability for our battery system and preferably a Unit that can be programmed for Time of Use. Most regions have tiered billing where overnight power costs are lower than during the day, so being able to charge your batteries when Grid Power is cheapest is a WIN (for the pocket book especially). In fact, many are doing time-shifting by running off battery during Peak Power Cost times and charging when Grid power is cheapest.
How many watts & what voltage to use.
In general, we say, not to pull over 250A from a battery system.
12V X 250A = 3000W or 120V/25A These are 4S (4 in series cells) *2
24V X 250A = 6000W or 120V/50A These are 8S (8 cells in series)
48V X 250A = 12,000W or 120V/100A These are 16S (16 cells in series)
* uncorrected for efficiency & losses.
*2 The number of cells in a battery pack for the required voltage. This also affects the Size & Weight of each battery pack.
Battery Packs can be pretty heavy & large.
--- 24V Battery (8S) examples. X2 for 48V
24V/100AH weight avg 19-20kg (41-44lbs) 2560Wh or 2.5kWh
24V/280AH weight avg 44-50kg (98-110lbs) 7168Wh or 7.1kWh
A POINT THAT NEEDS TO BE MADE: I run my Offgrid Home on a 24V System. It runs my deep well pump and even my heavy equipment like Compressor & Even my MIG Welder and more. I have Very Rarely ever pulled more than 150A from my battery system (just the awful draw surge from Welder & Compressor when under load... ugh, it's fugly but no burps)
A final thought.
Life changes all the time, I would suggest rather than an AIO, so with a good quality Inverter/Charger with the Good features that is programmable & flexible to suit your needs. One that can be paralleled to increase capacity IF needed and hat can also interact with Solar Controllers etc should you ever move & need/want to add more capability... Not getting locked into a fixed system is wise, being able to add on and build out with reliable companonets is protecting that investment. Therefore I would very strongly suggest Victron Equipment which has an entire eco-system with all of their gear that works together & most reliably. It can all interact & communicate which allows you fne control & monitoring capabilities. This is Tier-1 Product, so it costs a bit more but you can easily count on 10+ years without issues and their support is EXCELLENT !
Hope it Helps, Good Luck.
A Quick Tip:
If you want to back up everything you are running. Grab your Power Bills, look at the 3 Heaviest Months of use. Most give you the kWh used per month and some even break it down to weekly & daily BUT you can do that yourself. Once you know what you are using per day in kWh then you have a baseline of your requirement. Most folks then add triple (in storage) that for emergency buffer (mostly rural homes etc) or more pending on situation & need. In a city with apartments I would say that 2X is more than enough in general. So if you use 5kWh per day, a 10kWh battery system will do it nicely. ALSO A BONUS with LFP: You can add batteries over time WITHOUT bad consequences. You CANNOT do that with Lead Acid, AGM etc, only Lithum Based batteries.