This is already possible! Check this post for more information!
Basically, Obsidian does support exclusion of tags and paths. For example, I have a lot of webpages downloaded as .md that I keep for archival purposes. Since these are external sources, I mark them with #external. I don’t want these to appear on my graph view so I can just add “-tag:#external” in the “Search Files” box and it excludes every file with that tag. Cheers :3 Thanks to the OP of the thread I linked.