Recreating Database from IBD files (no FRM)
As suggested by @AMtwo, .frm files contain the schema definition. Since these are WordPress tables, getting the schema was very easy as I had lots of installs to get this info from.
I then followed the guide at https://www.chriscalender.com/recovering-an-innodb-table-from-only-an-ibd-file/ and it worked just fine:

Create table based on the schema of original table.
Running ALTER TABLE product DISCARD TABLESPACE;
Copying the original IBD file
Running ALTER TABLE product IMPORT TABLESPACE;

The tutorial mentions further instructions but at this stage it simply worked for me. I did the same for all other tables, exported as SQL dump and imported successfully.
I would recommend using Docker + mySQL if you are going to be trying this out.
Thanks again @AMtwo, you pointed me in the right direction!