Video Doorbell Transformer and Heat

I am installing a Nest Hello video doorbell. I’ve installed all new thick-jacket low-voltage wiring and a new 24V-20VA transformer to support 2 mechanical chimes. The transformer is installed in an attic full of deep blown-in cellulose insulation (same location where the old one was).

A regular doorbell only energizes the transformer "momentarily" when the button is pressed. My understanding is that video doorbells require "constant" power. But most transformers I've met start getting hot under constant power.

I've heard of cases when a regular doorbell button gets stuck, which continuously energizes the transformer, burning it up within hours. That tells me that these transformers were not designed for "continuous" duty cycle. Yet, Nest tech support is telling me that it's "perfectly safe", they do not expect the transformer to heat up much more than ambient temp and there are thousands of people using these setups nowadays.

So, my question is, if running under a constant power from a Video Doorbell will make the transformer run much hotter than with a Regular doorbell button?

Are there any factors, such as output wire gauge for example, that would help me keep the transformer temperatures down? Any suggestions on fire-proofing the install location, I can't move the transformer without much rewiring, but at least I did not cover it with insulation like the old one was. Should I find some fire-resistant materials (like HardiBacker) to surround the junction box + transformer to isolate them from contacting the cellulose insulation or is that too much?

Am I overthinking all this? I know I could just hook it up and see what happens. I just prefer not to experiment on things that could start a smoldering fire in an attic : )

I mainly don’t want to constantly worry about how hot the transformer gets in that attic full of loose insulation because it’s being used "continuously" rather than "momentarily".