Based on the above information, the official line is (I think) still 10x10 per company.
If you had a home brew chapter that was 20x5 I'm sure that'd be fine, or even 20 squads, even if some were 3 or some were 10 or whatever. Since our Codex lord and master returned from the grave the Codex so valued by his sons seems borderline redundant now.
I'm far from homebrew - it's the Ultramarines. So I'd have the following in a pure Primaris Company
6xbattleline squads (which can be Infiltrators, Intercessors, Hvy Intercessors) - all in Squads of 10 guys
2xclose support squads (Assault Intercessors, Reivers, Inceptors, Assault Aggressors, Outriders) - essentially 2 Squads of 10 guys which can break up and don the appropriate armour. So squad 7 splits up into 5 Reivers, 5 Assault Ints, while 8 goes for 3 Agressors, 3 Outriders and 3 Inceptors, with the last brother maybe riding in a tank or whatever (driver for a gladiator or whatever^^)
2xheavy support squads (Infiltrators, Bolter Aggressors, Hellblasters, Eradicators), again splitting up into, say, squad 9 being 3 Infiltrators, 3 Aggressors, 3 Eradicators and the last guy being the gunner of an forementioned gladiator. Squad 10 is 10 Hellblasters.
And then you have company command with the usual suspects.
Does that sound about right?