I purchased a Bosch electric lawnmower in 2010 and have used it ever since and the battery is still going well. As I already have the battery/charger, this would be a good idea, but if starting without these, expect to pay about $350 extra to have the complete kit but I also saw a 2Ah+charger combo for just under $200 https://www.amazon.com.au/Bosch-Lithium-Battery-Charger-Star…
The thing I love about electric mowers, much like cordless vacuums, is that it's just easy to grab it at a whim and mow your lawn because it's light and doesn't need maintenance. Very quiet compared to petrol-powered. And, as with all modern electric-powered devices, when in storage, keep the charge between 20 - 80% to get the best life out of the battery.
Also, if you have a smaller lawn, take a look at a complete Bosch 18v mower/battery/charger https://www.amazon.com.au/dp/B08GLNF9G7?th=1 $335 / normally $429
If you are already invested into a different battery system but you want to buy skins on sale like this, you can buy or make adapters. Saves the expense and pain of having different battery systems. As long as there is a little extra physical room it would work fine.