Loving the depth of this feature request @JohnCP, I got very excited about the idea of glowing neurons! “OR” filters would definitely a make a huge difference to the potential workflows, especially on the Graph View.
We have plans to completely overhaul how search and filtering works (to include OR operators, and multiple-parents etc), and this has already made it through the design stage. This will be another big big update though and we will possible tie this together with custom metadata, since the introduction of this will require the filtering overhaul. However for the meantime we are prioritising offline mode + building out our mobile apps.
Since using filtering with boolean operators and viewing your cards as a graph view are technically independent from each other, I would be tempted to rename this FR purely as “Add boolean operators to filters” – so we can link more easily to this topic in the future as I’m sure it will come up again. But I will leave that to your discretion @JohnCP!