With Apple Music you can only stream music via the app and on iTunes you can buy and save up the files and play them on any device that means you don’t really need an iPhone/iMac etc. But for the lossless aspect I mostly get my digital stuff on OTOTOY. There you can choose between a lossy and lossless format. I only buy from the iTunes store if it is unavailable outside of Japan. iTunes only provides AAC (lossy format) though but this is almost close to lossless quality.
We also have a similar thread where you can read further details about it: Buying from Apple Music