Can home assistant be installed after a rasberyy pi system is already on the rasberry pi and

I have a raspberry pi that has a system already on it. Its a 4th gen with 400mb of storage. The link for HA is to format the pi errasing all data. I have tried the program to install it but it wont work on windows 7

If you have already your Pi configured and you don’t want to wipe out all your disk, you can install HA in a container or in a virtual environment… See this page for more details:

Just buy another SD card for Home Assistant. Unless you want to run other programs on the same pi, then you have to go to the complexity of a virtual system.

Great Ideas I think there needs to be a warning that the easy diskwriter will only work on windows 10 and above I finally got it installed and now I am tickled.
Thanks for the help