sudomod

I'm posting this here in case people miss the other posting about it:

https://sudomod.com/forum/viewtopic.php ... 913#p63913

It's a boost board I made that can power up to 3.5A at 5.20v in interested follow the link above.

Do you know if it supports the function to charge and use it at the same time, as adafruits powerboost 1000c does?

Well if you have a charger that can provide the amperage to charge the battery and the device it's powering then yes but unless it's a 4A or 5A charger then no you can't really charge and play. The Pi 3 B+ with HDMI LCD Draw close to 3A so that means you will likely need a 4A charger to power it all and still charge the battery.