Free modified Swiss Tournament System

I propose the following Swiss-pairing system:

Round 1: The players are divided into four rating groups. The highest-rated player in group 1 has White against the highest-rated player in group 2. The same applies to groups 3 and 4.

Round 2: The highest-rated winner gets Black against the highest‐rated winner in the other half. The second-highest gets Black against the second‐highest in the other half, and so on.

Round 3+: Standard Swiss pairing begins. Players are sorted by points, then Buchholz score, then original rating. Pairing proceeds from the top downward, each player being matched with the next available opponent.

Colour allocation: The player who has had fewer White games receives White. If both have had the same number of White games, the player with the higher starting number (lower rating) receives White.

This system is suitable for open tournaments. Elite players can hardly complain, since they face lower-rated opponents in the first two rounds. In Monrad, the early rounds can be unfair, as one top player may face a strong opponent while another meets a weak one. At the same time, this system avoids the oscillation that mid-level players may suffer in other Swiss systems, namely alternating between opponents who are far too weak and far too strong.

The system can be tested online here: Swiss Tournament System

Pairing proceeds from the top downward, each player being matched with the next available opponent.

You did not describe an exact algorithm but from your description it seems that you don't take colour balance (and colour history in general) into account in the construction of pairing, only for colour selection. That would inevitably lead to some players having large colour imbalance (and, as a consequence, violating of basic rules for swiss system). In later rounds you would also run into impossibility of acceptable pairing for lowest ranked players so you should define the algorithm of handling that problem.

If you really want to invent a new flavour of swiss system, I would recommend to start with learning the essential constraints given by Basic rules for Swiss Systems and General handling rules for Swiss Tournaments. The next step would be getting familiar with the Duch System which is the most common flavour of swiss system in today's tournament practice and probably also with the alternatives (Dubov, Burstein, Lim) and accelerated systems, understanding what they aim for and why they work the way they do. Then you could analyze their weaknesses and try to come with a new system addressing those weaknesses without introducing more severe ones.

Elite players can hardly complain, since they face lower-rated opponents in the first two rounds.

I'm pretty sure that's something they would complain about quite a lot.

At the same time, this system avoids the oscillation that mid-level players may suffer in other Swiss systems, namely alternating between opponents who are far too weak and far too strong.

That's far from obvious. Can you explain why it should be the case?