I found a plugin to disable select Gutenberg blocks (https://wordpress.org/plugins/disable-gutenberg-blocks/). I installed it but have only been able to remove WP RSS Aggregator Feeds with this.

I also went into the parent theme and commented out the registration of the Image Banner block. This is a hacky approach that will require additional steps be taken for any updates of the site's parent theme. I have done this with reservations that this is directly contrary to best practices.

I have not been able to hide the WP Google Maps block without white-listing blocks to use on the site (which would hide all blocks not on that list). I will not use this approach unless I am expressly instructed to do so, as I believe this will take an inordinate amount of time/effort and is highly error prone.