Bitcoins and further crypto currencies can be bought/sold on following exchanges (selection):

Bitpandawww.bitpanda.com (get 10 Euro for registration and further 10 Euro for trading, Austrian company)

Bitcoin.dewww.bitcoin.de (market place of Fidor Bank, German  company)

Overview of crypto ratings of more than 200 cryptocurrencies and cryptotokens on Wikirating (notes: not all of them get a rating, the columns can be sorted:

Screenshot from Wikirating, as of January 11, 2021
Overview of crypto ratings from the top 15 cryptoassets (by market cap), screenshot from Wikirating, as of January 11, 2021

How to

How to buy Bitcoin(s) and co.

In English:

Auf Deutsch: