They added:

10. None of the Work may be used in any form as part, or whole, of an integration, plugin or app that integrates with Atlassian’s Confluence or Jira products.

Can’t you just not use their cloud services? It makes you create an account for setup, but once setup was done I never touched it.

I do not know what you mean by third-party integrations. I do not use any cloud stuff, Ubiquiti’s or otherwise.

I used to use OpenWRT on various devices, but two years ago I got a UDM-Pro, a USW-16-POE, and a few Unifi APs and cameras. I run pi-hole on the UDM-Pro. I have no complaints. It is more expensive than piecing it all together using OpenWRT and some Raspberry PIs, but way easier.

You could use multiple USB microphones and do the mixing in software. I prefer using an audio interface (e.g. UMC204HD) because it is simpler to set up and adjust levels, and because it lets you use any widely available microphone, or plug in an instrument (e.g.: electric guitar, electric piano). You can plug your headphones into the audio interface and adjust the relative level of your own sound and what is coming from the computer (e.g.: your teacher). sweetwater.com has the UMC204HD and the UMC404HD on sale right now.

I do not have any experience with pick-up mics.

I tried Jitsi, but was unable to match Zoom’s audio quality.

The difference between Jitsi and Zoom was noticeable, but less important than the difference between the mic built in to the webcam and good mics. I use an SM58 for voice and an SM137 pointed at the cello just below the bridge, through a UMC204HD.

My complaint is no so much the requirement of a phone number as the requirement of an Android/iPhone app.

The desktop app should be a first-class client.