manage disk spaces after installing ubuntu 20.04 alongside windows

Question

Probably I should have partitioned the disks before installing Ubuntu but I will give it a try.

I've noticed when opening my file explorer after installing Ubuntu 20.04 alongside windows 10 that it shows a bunch of empty local disk volumes. Here is an image of what I mean:

Please note that disks D: E: F: G: H: when clicking on them give me that the disk is empty. I wonder if they're really empty and I could merge them into only one single disk or if by attempting this most probably I will mess up my Ubuntu 20.04 installation.

This is my disk management information from windows side:

And the info on Ubuntu's side:

I'm not an expert on partitions,volumes and where the OS and bootable partitions,volumes are mounted and don't want to erase the hard work I have done on Ubuntu so far.

Edited: Here the output of df -h as requested:

Filesystem       Size  Used Avail Use% Mounted on
udev             7.8G     0  7.8G   0% /dev
tmpfs            1.6G  1.9M  1.6G   1% /run
/dev/nvme0n1p10   36G   30G  4.6G  87% /
tmpfs            7.9G   37M  7.8G   1% /dev/shm
tmpfs            5.0M  4.0K  5.0M   1% /run/lock
tmpfs            7.9G     0  7.9G   0% /sys/fs/cgroup
/dev/loop0       147M  147M     0 100% /snap/code/46
/dev/loop1        98M   98M     0 100% /snap/core/10126
/dev/loop2        98M   98M     0 100% /snap/core/9993
/dev/loop4        56M   56M     0 100% /snap/core18/1885
/dev/loop3        55M   55M     0 100% /snap/core18/1880
/dev/loop6        63M   63M     0 100% /snap/gtk-common-themes/1506
/dev/loop5       218M  218M     0 100% /snap/gnome-3-34-1804/60
/dev/loop7        51M   51M     0 100% /snap/snap-store/481
/dev/loop8       256M  256M     0 100% /snap/gnome-3-34-1804/36
/dev/loop9        31M   31M     0 100% /snap/snapd/9607
/dev/loop10       31M   31M     0 100% /snap/snapd/9279
/dev/loop11      147M  147M     0 100% /snap/code/47
/dev/loop12       50M   50M     0 100% /snap/snap-store/467
/dev/nvme0n1p9   511M   24K  511M   1% /boot/efi
tmpfs            1.6G   76K  1.6G   1% /run/user/1000

Answer 1

As far as I can tell the first 4 of those 512 MB partitions (D-E-F and G) are not actually used. H appears to be used by Linux (it looks to be the /boot/efi partition mentioned in the DF output).
In theory you could merge D-E-F and G, but that would change the partition numbering scheme in such a way their either Linux, Windows or both become unbootable.
That can be avoided but is very complicated. I certainly won't try to explain how to do that. Too much room for error with bad consequences.

Since the total space is only about 2 GB I wouldn't though them. Safety first.
The only thing I would do in the Windows Disk-Administrator tool is to remove the drive letters from D,E,F,G and H so these partitions become invisible in Explorer. This will prevens you from doing accidental damage to them from within Windows.
Especially important for H: as this is also used by Linux.

You could leave the drive-letters on D, E, F and G and use them as small data disks in Windows if you want. Re-formatting them as NTFS should be OK too.