Day 1 of using Nostr. What the heck are zaps?

1 rabbit hole later I have more new questions then I had questions answered but that’s life.

But, and here I #asknostr it seems to me that since self-custodial (that is, decentralized networks) are the preferred way to go if you want control and privacy, but lightning networks (#lnurl) are faster and easier, I need to go for a two step rocket.

Do I understand correctly that since lightning enabled wallets have to make use of a centralised service for network costs, this is where I would have very liquid assets, and then I would transfer it (like once a week or once a month, depending on volume) to a self-custodial wallet and as such only infrequently incur the higher network costs ?

Thanks for anyone that can give this noob some Pointers!