A few tricks that I've used to augment my searches. Note boolean algebra above. However, using the comma (OR) often restricts the number of results rather than increasing the number of results. In true logic, "OR" should ALWAYS increase (or give same) results. So, sometimes doing separate searches rather than combined searches provides more results.
Also note, I've never been convinced that E-Bay effectively deals with suffixes. "S", "ED", etc (one of the reasons wild cards are important).
Left hand column has various ways to improve searches. I'll click on "Item Location Worldwide". This will bring up more sales. This still limits based on shipping location. If you really wish to go full rogue, try some of the European websites:
https://www.ebay.it/
https://www.ebay.fr/
https://www.ebay.de/
https://www.ebay.co.uk/
https://www.ebay.com.au/
You may have to talk to sellers directly about shipping quotes. But, you often get different search results. But, this will help when searching for large purchases of items that are rare in the USA.
If I have too much junk, then perhaps exclude China (North America Only), or simply choose "Used".
The left column choices vary by subcategory (including using their "See All", and can be helpful, but don't depend on them too much. It is getting better, but I think stuff is often miscategorized or missing the category designations.
There is cycling stuff that gets miscategorized. So, bumping up a few menu choices can help. "Cycling". Also, my searches often fall on the division between "Vintage" and "Modern", so either search "Vintage" separately, or choose a menu level that includes both.
You can never count on a derailleur actually being posted under derailleurs, or front/rear being correct.
There is also a category:
Collectables/Transportation/Bicycles.
I find this category most frustrating. I understand why they have it there, but there is so much overlap with "Vintage Bicycles", and I often forget to include it with my searches. Ideally there would be a way to cross searches into that category.