I feel, we as a fandom, don’t talk enough about Aziraphale's singing.
Maybe he's not much into whatever pop/rock sensation is currently in most humans earphones*, but we know that he used to be a music tutor and therefore surely knows many great tunes.
On top of that, his music taste isn't as ancient as some might think... yes he likes classical music, but contrary to some opinions of it, not all of it is from 18th century.
The symphony (number 5) he buys from Maggie at the beginning of S2 was written in 1937 by Dimitri Shostakovich who had a turbulent life (it being the 1930s AND trying to survive in Stalin's cruel regime).
The piece the Bentley plays for Azi when he asks for music on his way to Edinburgh is one of my favourite pieces of music called Danse Macbre by Saint-Saëns, the opening of which Wikipedia describes thus:
The piece opens with a harp playing a single note, D, twelve times (the twelve strokes of midnight) which is accompanied by soft chords from the string section. The solo violin enters playing the tritone, which was known as the diabolus in musica ("the Devil in music") during the Medieval and Baroque eras, consisting of an A and an E♭—in an example of scordatura tuning, the violinist's E string has actually been tuned down to an E♭ to create the dissonant tritone.
Aziraphale is also clearly aware of the film and the music + songs from The Sound of Music (1965) and Aziraphale, living in Soho as he does, I bet is a great lover of not just drama in theatre, but also musicals.
Therefore it is not a huge reach to conclude he would knows some fabulous songs to sing while making himself a pot of tea and a cup of coffee for Crowley on one the countless idyllic mornings in their cottage. Nor is it a stretch to assume that he loves to sing Crowley to sleep, playing with his hair as he does so, much like we all love to see in art and fics that this wonderful fandom provides.
So my question is, what does Aziraphale love to sing? Is it Maria from West Side Story? Singing in the Rain?
Does he love Jesus Christ Superstar (much like he loves his collection of misprinted Bibles)?
Did he and Crowley go see Hamilton?
I also think they would have a huge collection of instruments in their cottage, perhaps even a beautiful grand piano... that, of course, they both can play.
*but neither is the Bentley, who plays Queen to Crowley basically indiscriminately, even though he tries to play other things when driving. Whether he tried to play music in his car before the 70s, I'm not sure we know?