I've been very happy with my amboss magma lease https://magma.amboss.tech/buy You pay for the inbound channel size you want and they can "auto refill" to ensure you always have the inbound you want/ need.
Outside of that, I've used Captain coincept.com and lnbig.com and Zeus/olympus https://channels.zeuslsp.com/ and all will eventually close slow/low volume but they're great for large/high volume channels.
Lastly I prefer to have multiple channel partners instead of one fat inbound for routing optionality.
PS just downloaded your book and so far looks great! Thank you for writing it and I hope you sell a ton!
