Quoting myself from Guidelines for closing as off-topic, belong on a different SE:

Migration in general is a thing we prefer not to do. Sometimes a good question simply gets posted at the wrong site; it should be closed first to determine that it is off topic, then flagged for migration. In borderline cases we moderators have to investigate if it is on topic at the target site, because migrations can be rejected and we don't want to give more work to other moderators. We do not have migration paths, because we hardly ever use this feature in the first place. There simply is not enough data, to support setting these up.

For further clearing up:

Why are other SE networks not shown here like Physics.SE (many questions fit there better than Chemistry.SE), Maths.SE etc?

Just because a question is better suited at another site, it does not mean it is off-topic here, hence it is no reason for migration. In any case, migration should be reserved for very occasional cases and there is no evidence to support that we actually need migration paths; i.e. there are too few cases so that we could actually benefit from user driven migration.

Please vote to close on question you think do not belong to our site with a custom reason explaining your reasoning. Once a question is closed, flag it for moderation. The team usually investigates whether the question is on topic on the target site, to avoid that a migration is rejected. In most cases, we do not migrate open questions (It has to be decidedly off-topic first).

Quoting myself from Guidelines for closing as off-topic, belong on a different SE:

Migration in general is a thing we prefer not to do. Sometimes a good question simply gets posted at the wrong site; it should be closed first to determine that it is off topic, then flagged for migration. In borderline cases we moderators have to investigate if it is on topic at the target site, because migrations can be rejected and we don't want to give more work to other moderators. We do not have migration paths, because we hardly ever use this feature in the first place. There simply is not enough data, to support setting these up.

For further clearing up:

Why are other SE networks not shown here like Physics.SE (many questions fit there better than Chemistry.SE), Maths.SE etc?

Just because a question is better suited at another site, it does not mean it is off-topic here, hence it is no reason for migration. In any case, migration should be reserved for very occasional cases and there is no evidence to support that we actually need migration paths; i.e. there are too few cases so that we could actually benefit from user driven migration.

Please vote to close on question you think do not belong to our site with a custom reason explaining your reasoning. Once a question is closed, flag it for moderation ("... in need of moderator intervention"). The moderator team usually investigates whether the question is on topic on the target site, to avoid that a migration is rejected. In most cases, we do not migrate open questions (It has to be decidedly off-topic first).