The sda1 and sda2 partitions seem safe to format. Just be sure that you really copied everything you need from there. Like others said, better not to mess with the boot partitions
If you want to increase the space of the linux partitions, insead of creating a new extra partition, that may be a bit tricky in that layout, but one thing you can do is (from a live boot) is:
1- delete both windows partitions and create a new ext4 one with ~530gb
2 - clone your /home partition into there and change the fstab to point to the new partition
3- manually check if all your files were safely copied, just to be sure
4 - delete the old /home and expand the size of the / partition into it
you will end with a / partition with ~300gb and a /home of ~530gb





I started running foss apps and loving how small and efficient they were in comparison to what I was used to. At one poit I realized that everything I was using could be used on linux, so I migrated and never went back!