I suspect this this may be a duplicate, but I'm not sure what I should do considering almost everyone else has another macOS version or other partition size and I'm not sure how to generalize another answer to my setup.
So I wanted to delete a Linux partition back to APFS on my main HDD, but it split up the
APPLE SSD SM0256F Media. I'm still on my macOS system, but I know that if I reboot I won't be able to access it. I've made a backup but would like to make the partition bootable/accessable since I can't backup programs etc. I still have a 16GB USB drive for use if that's necessary. Also Macintosh wasnt split up as it is now. Macintosh was the main drive that showed up in Disk utility.
/dev/disk0 (internal, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *251.0 GB disk0 1: EFI EFI 209.7 MB disk0s1 2: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF 205.8 GB disk0s2 /dev/disk1 (synthesized): #: TYPE NAME SIZE IDENTIFIER 0: APFS Container Scheme - +205.8 GB disk1 Physical Store disk0s2 1: APFS Volume Macintosh HD 122.9 GB disk1s1 2: APFS Volume Preboot 45.8 MB disk1s2 3: APFS Volume Recovery 517.0 MB disk1s3 4: APFS Volume VM 2.1 GB disk1s4 /dev/disk2 (external, physical): #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *15.7 GB disk2 1: EFI EFI 209.7 MB disk2s1 2: Microsoft Basic Data SD CRUZER 15.5 GB disk2s2
gpt -r show disk0
start size index contents 0 1 PMBR 1 1 Pri GPT header 2 32 Pri GPT table 34 6 40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B 409640 401934440 2 GPT part - FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF 402344080 87890639 490234719 32 Sec GPT table 490234751 1 Sec GPT header