Here's what I use:

• YouTube:
  • LibreTube has really nice UI/UX and integrates SponsorBlock and DeArrow. It relies on Piped for fetching subscriptions (since the newest version it will play just fine with a broken Piped server though).
  • NewPipeX is what I use when LibreTube doesn't work and for downloading YouTube content. It is a fork of NewPipe which integrates SponsorBlock.
• Mail:
  • I use posteo.de as a provider, but it isn't fully liked here due to it not supporting custom domains.
  • mailbox.org is another solid provider (with support for custom domains AFAIK) if you don't want to use Proton for E-Mail.
  • FairEmail is my mobile client of choice (Geary or Thunderbird are good for Desktop).
  • k9 Mail is an equally good choice.
• Cloud Storage:
  • For Cloud Storage I prefer the selfhosted Seafile.
  • If you just want to share files temporarily, Wormhole is a good tool for that.
• Gallery App:
  • Aves Libre is solid if you don't want to selfhost, but it doesn't have fancy features like automatically (od manually) detecting faces.
  • Immich is pretty much the selfhosted Gallery app.
• Video Player:
  • Just (Video) Player is what I use, but honestly the stock player should be fine.
  • VLC will play pretty much anything you throw at it, but I don't like its UI that much.
• Music Player:
  • Vanilla Music is alright, but nothing special. Musicolet, while not FOSS, is a privacy respecting Music Player that has a bunch of handy features, most notable one for me is the ability to have multiple queues.
• 2FA App:
  • Aegis has never let me down, although you should keep in mind it doesn't have any sort of cloud sync.

For password manager and weather I use the same apps as you.

I run a Pixel with GrapheneOS. I actually also came from Samsung, and for me there are quite a few creature comforts missing that I didn't even think about (eg. Samsung Dex, DP altmode, I really like the One UI Dialer, Miracast, Brightness Slider in notifications, switching recents and back button, headphone jack, SD card slot, ...).

As for the Pixel being worth it, I'm ok with it as I was due for an upgrade anyway (Galaxy S10 -> Pixel 6). I'd recommend, if you value your privacy and are fine with losing some Samsung features, to either go all the way and upgrade to a new Pixel when your S23 gets old / dies or buy a cheap used Pixel (Pixel 6 and 7 currently has pretty decent value) to just test it out.