Thanks.
Would it also work if I started out without the pruned flag and added it later (culling disk space effectively)?
What about the case of a non-pruned node that's running with neither flag and then I restart it with block filters?
The block filters are created during the synchronization phase. You would need to know the blocks as you are building the corresponding block filters, and block filters should not be generated upon request; they should be generated and kept locally to be served to the peers.Would it also work if I started out without the pruned flag and added it later (culling disk space effectively)?
What about the case of a non-pruned node that's running with neither flag and then I restart it with block filters?
Hence, your block filter should be present after your IBD. You can prune after you've synchronized fully, or you can prune as you go. If you have a non-pruned node without block filter but decide to enable after, then you need to reindex as well to build it. Note that blockfilterindex provides for the filter and the peerblockfilters allows your peers know that you're able to service BIP157 and serve them the filters.
