A layer-1 blockchain is a set of solutions that improve the base protocol itself to make the overall system a lot more scalable. There are two most common layer-1 solutions, and these are the consensus protocol changes as well as sharding.

https://coinmarketcap.com/alexandria/article/foan-continues-strong-fundamentals-growth-in-january-push

https://coinmarketcap.com/alexandria/article/fast-food-firm-up-460-by-investing-profits-into-btc

https://coinmarketcap.com/alexandria/article/kpmg-canada-invests-in-bitcoin-and-ether

https://www.crypto-news-flash.com/litecoin-launch-the-mimblewimble-upgrade-sending-ltc-up-by-5-5/