Dual boot (Mac/Linux) iMac can not boot after delete partitions

I had a dual boot (Mac/Linux mint) iMac (2017 27″) for about a year, recently my imac has not enough space so i wanted to remove linux mint.

In Disk Utility, I delete a 7 GB SWAP partition and a 20 GB partition for sharing files and merged with the partition where Linux mint 21 was installed.

After that, MacOS can not boot.

I ran MacOS recovery mode, in terminal I saw the drive info like this:

Disk0: 
0:GUID_partition_scheme                  *1.0 TB    disk0 
1:EFI EFI                                 209.7 MB  disk0s1 
2:FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF    841.7 GB  disk0s2 
3:Linux filesystem                        120 GB    disk0s3

the 2 one, disk0s2 with strange name FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF should be the partition where MacOS is installed.

For reference I found a post here in SuperUser which is a little similar problem, unfortunately my knowledge of running codes in terminal is very poor, i don’t understand very much those commands. But I will continue trying.

I tried also in MacOS internet recovery mode to reinstall MacOS, but there is no disk for me to choose to install. 🙁

I reinstalled Linux Mint on this 120 GB partition, which runs well, unfortunately it’s impossible from there to access files in MacOS partition which are my most concerns. Is it a way to access MacOS files from Linux Mint or some other methods?

Is the disk0s2 partition repairable so the MacOS will be able to boot?

Any suggestion, insights, helps will be highly appreciated. Thank you so much.