You don't need an address on the NIC either when have an host side MACVLAN. The key is you only need one address and the prefix length can then be / should be /22 and no conflicting prefix route will be added. Since there's is only one BD and one subnet, it does not matter whether you docker host have a .1.x or .2.x.

But certainly, if you have some sort of "symbolism obssession" whatsoever, like "I want it to look obvious that it belongs to both types blah blah blah", it's probably fine to have both added as a /32 and then add a /22 prefix route manually.

However, even in that case, having both addresses configured on the MACVLAN probably makes more sense (as in, it should be less problem-prone practically that way).

It's just like when using a bridge you don't configure address on the bridge slave NIC, though in the case of MACVLAN, technically the attached NIC can still be used as the "exit point".

As for how to use an existing bridge as a docker bridge, I'm not entirely sure. I just assumed it is possible. Maybe it is, maybe it isn't, maybe it is but very inconvenient, I don't know. RTFM if you are interested.