Don’t really have a recommendation about which, but I do about how.
For repositories that I deem important, either for practical or nostalgia reasons, I use Gitea to keep an up to date clone. I believe most self hosted Git solutions offer a similar functionality, like Gitlab has one too that I’m aware of.
Something like DigitalOcean or Hetzner will set you back a max of 10 euros a month. But that does require some technical know how with a terminal.
Would that suffice, or are you looking for something more ‘UI Based’ that will manage it for you?