Authy was never open source, nor self hostable, nor did it allow you to export TOTP tokens. You also don't have to use their own TOTP format if you don't want to, in fact I've yet to see any website that actually uses it. The equivalent to Bitwarden when it comes to managing 2FA would be something like Aegis, which is open source and has feature parity with Authy.
If the parent means the 7 digit style when referring to authys own topt format: Cloudflare and humble bundle use those. Thankfully Aegis also supports these.
[0]: https://getaegis.app/