This subject has been discussed earlier but not directly about ACF blocks or MB blocks.
Since we got support for ACF flexible content earlier this year it should be possible to support ACF blocks. ACF Blocks is “flexible content 2.0”!
This would allow us to use bricks templates (or sections) as Gutenberg blocks (or ACF blocks).
It would enable a great new way to build new blocks into Gutenberg blog content.
For agencies its important to have one editor for clients to use and its good to use something that’s native WordPress
ACF Blocks: ACF | Blocks
Metabox Blocks: MB Blocks - Creating Custom Gutenberg Blocks With PHP - Meta Box