Hey, you can easily swap your SOL with sats on LN using fixedfloat.com. Unfortunately the SOL - LNBTC pair is now suspended. Maybe later on huh ?

Good choice not to use onchain with small tx ( fees are high these days ). Better to store adequate amount of sats to spend it later ( in case you would need it )

Anyway, you need inbound liquidity on LN. Think of it as a " can receive " amount. If you have no more inbound liq you can't accept more payment.

You can go to the Phoenix path and once you no longer have inbound liq, you can spend your sats slowly or looping out

Or harder, wilder & better approach would be using Blixt wallet ( or Bitkit? ) and buy inbound liq from LSPs such as Blocktank, Deezy, LNBIG or Thor.

Self custodial is a damn complex task to do, you can ask for someone's help here & be careful not losing your backup!