Looking for screw size and type for my P1

I just recently got a P1 in the mail, and worrying about battery corrosion I decided to pop the back off and change the batteries. I wasn't aware of how soft the screws would be and.... I stripped them horribly! But I am super lucky that my husband works with small electronics and had the tools and know how to remove the screws. But now I am left with no screws at all for the backing. I have searched the internet to try and find what type and size screws I need for the P1 but I can't seem to find anything. Lots of info on how soft the screws are and ways to remove them when they are stripped. Is there anyone out there that knows what size of screw that can help me out?

https://japanyouwant.com/product-category/tamagotchi/tools

Japan You Want TMGC store has a listing for replacment screws for "old models" but it doesn't say what size screw.

There's also an old topic on this forum that discusses various methods people have used to replace the screws, but again there is no mention on what size of screw.

https://www.tamatalk.com/IB/topic/182795-replacement-screws-for-vintages/

Thanks so much! I will look into both of those things, I am planning on buying a P's soon so I can just add some screws onto my order whenever I choose to finally do it.