Typically when I want to export something, it is a seed swap list, but I could see using it on "my plant list" if I spent a lot more time updating "my plant list".
I usually have to do some tweaking after I copy-paste from any web site into a Word doc or Word table.
For other websites, I use search-and-replace to add commas or tabs.
A manually-created file like that can then be imported into a spreadsheet, usually as a CSV.
But when it is inconvenient to import and export from a site, I just don't use that inconvenient website as a way to store information that I want to be able to recover and manipulate. While I'm working full-time, data entry and recovery has to be very easy or I won't spend time. After retirement may be a different story.
Seed swaps here are the only area where my motivation is great enough to motivate me to do the manual conversions, and I think the last time I tried, the "printer-friendly" version of some swap screens made the manual steps easy enough for some purposes. But I decided not to use the ATP database / seed list feature as my "inventory control system".
