Need to pull XML objects of all the searches in the system. Is SDF the only option? Basically want to find out all the searches which are using a particular record/fields in it. And that record is being refered in various places as a we are using it as a source list for a custom field in many places.

SDF is probably your best option to download them all, but the filters and columns in the resulting XML are encoded for saved searches so it's likely you won't be able to search for specific fields.

I can't search field internal id in the XML object?

Saved searches in SDF look like the screenshot below. You can take the encoded definition and use a tool like this to decode it to a searchable XML format. It's a pain.

Can write a python code then to decode it hopefully. Thanks for the info.

Here's an older thread with a CLI command to decode. https://archive.netsuiteprofessionals.com/t/23447893/when-pulling-a-saved-search-object-into-sdf-are-we-able-to-d