ralph.ronnquist wrote:

I know that some people feel good about running an "Expert install" even though their need for that is nil

Just for the record, I feel at home using Expert install. I like to see all the options and answer all the cuestions. I did so in my first Debian instalation as a teaching tool for mysef and I do now (20+ years later) to see easily what is going on. Just my 0.02 currency units.

@Élisabeth it appears you are using "Expert install" method and are skipping the "load components" step. (Otherwise you would have an ext4 formatting option)..

@Élisabeth it appears you are using "Expert install" method and are skipping the "load components" step. (Otherwise you would have an ext4 formatting option).

May advice on that would be: Don't. [...]

Your install is behaving un-normal. That no EFI partition is possible may be due to that the installer possibly is started in legacy mode.

I am sorry I don't get what you are doing, and why you have problems like not being able to set the boot flag and why ext4 isn't available. Are you using Manual Partitioning? This is recommended for an individual setup as you like it.

Steps:
1.) Highlight the disk where you want to install (sda, nvme....) and press Return (RET). You should be asked if you want to create a new partition table. Say yes and choose gpt (I just did that in a VM). May you have created partitions already, does not matter, they are getting deleted.
2.) When thats done, in the next screen you should see the disk and below that a line that says free space xxx GB. Move the cursor to the free space and press RET.
3.) On the next screen select "Create a new partition", press RET. Specify 256M as size, Beginning. Press RET.

4.) On the next screen first scroll down to Use As (ext4 should be presented as default). Press RET. You should get a list with 15 choices starting with ext4, ext3, ..... , Do not use.
5.) Select EFI System Partition and press RET. You should get a screen where the name is empty, the bootable flag is already set. You can't specify any mount point here, this is done automagically by the install process.
6.) [...]
7.) [...]

8.) On the next screen move the cursor to the large free space below the EFI partition. Press RET. Specify 64G, beginning, RET. Note: the installer leaves 1M empty before the EFI partition.
9.) Again you should see a screen that starts with Name, then Use as (you should see ext4 as default). You should leave everything at default, and just modify Name and Label. When you are happy move down the cursor to "Done setting up the Partition" and press RET.

10.) Same game for the swap partition. Specify 16G and beginning. USE as Swap partition. Done RET.

Now you should have the disk split up in 256M EFI System, 64G for /, 16G for Swap and the rest for /home.

1.) 256M as "efi system partition", will be formatted as FAT32, bootable flag set, name is your choice (not required), will be mounted to /boot/efi later on. Will hold the efi starter.

3.) Unencrypted root: since you have a 500G disk/ssd I would spend 64G for /root.
5.) Rest for /home, ext4, name to your choice again.

If you go for an unencrypted install which is much easier for a beginner, no separate /boot is required.

Stop, that not right. You need to go for an efi partitioning scheme. If you are getting asked, use GPT not msdos.

2.) 1024M to 2048M for /boot (but only if you want to encrypt your root). ext4, name is your choice (not required)

My suggestion:

• 512MB for /boot

• 40GB for /

• 8GB for swap

• the rest is for /home