Yes, there are several systems that work in the way you describe, where the off-camera lights can switch between different TTL systems, and the only thing you need is an on-camera transmitter unit that matches the camera system (i.e., "speaks" the correct electronic flash protocol, and has a physical foot pin configuration that matches the contact configuration on the camera hotshoe). The systems that do this include:

• Godox 2.4 GHz "X" system
• Jinbei TRQ triggers [also Westcott FJ/Rollei Freeze, see footnote]
• Nissin Air system (with the Air 10s commander)
• Phottix Odin Z system
• Profoto Air Remote system
• Broncolor RFS 2.2 transceivers (heavily modified Godox X triggers)

Canon, Nikon, Sony, and Fuji are the most commonly supported systems. Godox is probably the most popular for supporting six camera systems (they also do Olympus/Panasonic and Pentax) and having the lowest price tags on the speedlights/triggers as well as having speedlights, bare bulb flashes, and studio strobes in their system.

But these all rely on built-in radio triggers in the same-brand lights with a single exception: the Cactus X-TTL system. This system allows for cross-platform use of any TTL-capable speedlights since their add-on transceiver can do cross-brand TTL/HSS switching, unlike Godox's X1R add-on receivers.

And if you want TTL, naturally, the light itself must be capable of TTL; some of these systems integrate both TTL and manual-only lights.

However, in the Godox system, at least, when a new camera system is added to the Godox system, already-existing lights must be firmware updated to perform the cross-brand TTL switching. For example, Godox only recently added Pentax P-TTL support, and firmware updates have been issued for the AD600/AD400/AD200 strobes and the V860II speedlights, but the AD360II and TT685 speedlights have not received such an update and cannot (yet) switch to perform P-TTL.

I have a Godox TT685-C (for Canon) TTL/HSS speedlight that I had to upgrade the firmware on, but that I can now control over radio in TTL/HSS with remote power control from a Godox XPro-C transmitter on my 5DMkII, an XPro-O transmitter on my Panasonic GX-7, and an XPro-F transmitter on my Fuji X100T. And the flash will indicate on the LCD display which "brand mode" it's currently in:

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footnote: The Jinbei TRQ-7 and some select Jinbei RT 2.4 GHz-equipped strobes and a round-head speedlight have become rebranded as the Westcott FJ (in North America) and Rollei Freeze (in Europe) systems. These rebrands are exclusive in distribution and are now incompatible with the Jinbei-branded versions. But this is the only system that has a transmitter/speedlight that sports a 'universal' TTL foot: one with a pin arrangement that can cover all the traditional hotshoe contact placements. It still requires an adapter to work with the Sony multi-interface hotshoe and will likely require another one for the Canon multi-function hotshoe with their foot front-edge electronic contacts.