Another easy way, is just to look at the filesystem partitions.
Filesystem Size Used Avail Use% Mounted on
devtmpfs 4.0M 0 4.0M 0% /dev
tmpfs 32G 54M 32G 1% /dev/shm
tmpfs 13G 1.9M 13G 1% /run
/dev/nvme0n1p4 30G 16G 15G 52% /
tmpfs 32G 172K 32G 1% /tmp
/dev/nvme0n1p8 1.8T 122G 1.7T 7% /home
/dev/nvme0n1p5 20G 13G 7.0G 66% /var
/dev/nvme0n1p2 2.5G 294M 2.3G 12% /boot
/dev/nvme0n1p1 195M 6.1M 189M 4% /boot/efi
/dev/nvme0n1p6 15G 1.5G 14G 10% /var/log
/dev/nvme0n1p3 40G 1.1G 39G 3% /opt
tmpfs 6.3G 3.3M 6.3G 1% /run/user/1000
If you are using legacy BIOS, you typically cannot see the /biosboot partition using the "df" command.
However fdisk will show you. ( WARNING: Be very careful in fdisk )
fdisk /dev/sda
Welcome to fdisk (util-linux 2.35.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sda: 260 GiB, 279172874240 bytes, 545259520 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 005392C2-8A3E-4BAB-8697-A09E12798F8E
Device Start End Sectors Size Type
/dev/sda1 2048 6143 4096 2M BIOS boot
/dev/sda2 6144 6297599 6291456 3G Linux filesystem
/dev/sda3 6297600 396236799 389939200 186G Linux filesystem
/dev/sda4 396236800 413014015 16777216 8G Linux swap