BitFi

Here is the summary of current Dapps mostly used on Bitcoin (excluding Lighting apps). 

Stack is the smart contract layer of Bitcoin with PoX (Proof of transaction) which generates BTC rewards.
​https://www.stacks.co/

Hiro wallet is both browser and desktop wallet for stacks app.
https://www.hiro.so/wallet

You will need hiro desktop to solo stake STX. APY is 7 - 11% currently. 

Stacking detail is here;
https://stacking.club

You will need 140,000 STX = 57,400 USD as of now to stack solo

Or 

Stake here for less amount and you will also get NFT
https://boom.money/nft/boombox

Alex is the most used Bitcoin Defi app as of today.
https://app.alexlab.co/swap

There is huge farming reward at the STX/ALEX pool.
Single staking with Alex is also over 100% APY.
Alex platform has IDO (ICO platform) and lottery and also doing Alex lockdrop reward which is distributing reward for Auto Alex holder. 

Alex is also working closely with Bitcoin monkey NFT project.
https://bitcoinmonkeys.io/

These monkeys are traded on these 2 NFT market.
https://byzantion.xyz/collection/bitcoin-monkeys-labs
https://gamma.io/collections/bitcoin-monkeys

These are the summary of current BitFi ecosystem. Not much yet but it is getting bigger.