Turris OS 4.0.2 is out!

Dear all (including Viktor, who still spoils English section with Czech replies),
I’d like to ask whether you can advice in two items:

1/ Some time ago, I read that there is ongoing activity in Turris team to publish migration tool TOS3.x -> TOS4.x. At least, I need to migrate smoothly VPN since I hardly can push new VPN keys to all clients simultaneously. I do understand that other customized services can hardly be migrated…

2/ I’d like to test TOS4.x with chance to easily revert back to running TOS3.x, by having dual-boot as described in https://wiki.turris.cz/doc/en/howto/omnia_booting_from_external_storage. Is there any special reason why all steps described in article must be done with serial console access and can’t be done with SSH? Which particular step can’t be done with SSH?

Thanks in advance to both public and TOS team members!