This feels like a bit of a "you must exist in society" situation. If you rule out every company that does any business with Israel you will have a hard time buying anything.
First time I'm hearing of BDS. Looks like they want to boycott companies that help oppress Palestine (just going off of their homepage here). Since I don't know them, I'll speak generally of boycotts such as against e.g. Nestlé: Saying it's futile because you can't do it perfectly seems silly to me. You can't do everything right in life but you can try right? Minimise harm (as you see it) even if you can't take it away fully
The suggestion here is to boycott a printer because it uses a print head part from HP who sells servers to Israel.
The number of steps here is enough that you could rule out everything. And anything you think is left is just something you aren’t aware of a chain that links them.