Possibly not serious (or as established/large as CVP site).
What I would have in mind for a real 'Federation' of Chess Variants, if I were to dream big, would be something that included organized over-the-board play of chess variants in various countries globally, under the umbrella of a FIDE-like global chess variant federation. However, Canada or the US, for example, have their own Federations for chess, in some ways subordinate to FIDE, at least when it comes to serious international chess competitions or decrees about occasional minor changes to the rules of chess play itself.
Continuing to dream big, chess globally has tournament directors and organizers for international chess events. FIDE also manages an international chess rating system of its own.
CVP site already has much of what it takes to be a federation online exclusively in my early estimation, except for scale of membership, abundant tournament organizers, and taking in cash entries for tournaments (for those participants of any paid entry events who are willing to pay), like in the case of the official Arimaa site, if an online example is needed. I cannot recall just now what tournament format is used there - maybe knockout (seems good so an event does not last for months, or unless a relatively fast time control is used).
A possible big obstacle for chess variant federations/clubs/events is deciding which chess variants are to be included or excluded (and whether just for a particular time and/or place/event). CVP site solves this issue well with Game Courier. If necessary there could be separate federation(s) for popular single CVs such as bughouse, for example, but then why would they choose to be under an overall chess variants federation? A similar story for any regional chess variants' federations, e.g. of Shatar (Mongolian Chess). Also worth noting, Mind Sports includes not just chess variants but other games; it's possible a division of Mind Sports could be dedicated just to CVs.
It's easy to dream, especially if no potential federation founding organizer(s) want to fit all the details together just yet...
Here is a link to something online calling itself The Variant Chess Federation:
https://www-chess-com.translate.goog/fr/club/the-variant-chess-federation?_x_tr_sl=fr&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=sc
Possibly not serious (or as established/large as CVP site).
What I would have in mind for a real 'Federation' of Chess Variants, if I were to dream big, would be something that included organized over-the-board play of chess variants in various countries globally, under the umbrella of a FIDE-like global chess variant federation. However, Canada or the US, for example, have their own Federations for chess, in some ways subordinate to FIDE, at least when it comes to serious international chess competitions or decrees about occasional minor changes to the rules of chess play itself.
Continuing to dream big, chess globally has tournament directors and organizers for international chess events. FIDE also manages an international chess rating system of its own.
CVP site already has much of what it takes to be a federation online exclusively in my early estimation, except for scale of membership, abundant tournament organizers, and taking in cash entries for tournaments (for those participants of any paid entry events who are willing to pay), like in the case of the official Arimaa site, if an online example is needed. I cannot recall just now what tournament format is used there - maybe knockout (seems good so an event does not last for months, or unless a relatively fast time control is used).
A possible big obstacle for chess variant federations/clubs/events is deciding which chess variants are to be included or excluded (and whether just for a particular time and/or place/event). CVP site solves this issue well with Game Courier. If necessary there could be separate federation(s) for popular single CVs such as bughouse, for example, but then why would they choose to be under an overall chess variants federation? A similar story for any regional chess variants' federations, e.g. of Shatar (Mongolian Chess). Also worth noting, Mind Sports includes not just chess variants but other games; it's possible a division of Mind Sports could be dedicated just to CVs.
It's easy to dream, especially if no potential federation founding organizer(s) want to fit all the details together just yet...