IDK, I'm about as far from an expert as you can get so that's why I wanted more eyes on discussing this... my understanding with pruned nodes was that it downloads everything, then prunes it down.
Let's say you create a new Electrum wallet & connect it to your Mandacaru node, on the Mandacaru side can you mark your client connection as "don't look back, it's new" then does your node take note of the Bloom filter but ultimately only accumulate UTXOs from peers that fit your filter after it connected? The peers see that your node is downloading all new UTXOs but they don't see that your node is insta-pruning them if they aren't relevant to your wallet addresses?
But if you're having the Mandacaru node filter for your imported Electrum wallet that was already filled with UTXOs, it has to process the whole UTXO set to find them all but also do it in stages so it doesn't have more than however little MB stored at a time vs gigabytes?
I'm reminded of
https://walletscrutiny.com/android/de.schildbach.wallet/ which was all-in-one node & wallet but I only watched it run & poked around changing settings without actually receiving to/spending from its wallet.
