MWBC for split kitchen receptacle
There are a couple of tricky ways to do what you're after, but they aren't all that great
It is still possible to run kitchen small appliance branch circuits as split-receptacle MWBCs (vs. double-duplex MWBCs or solutions based on separate branch circuits), but it takes some panel gymnastics to do so for the reason you describe (namely, the lack of two-pole DFCIs on the market).  In particular, you have the choice of:

a GFCI protected common feeder using a 2-pole, 50A GFCI to protect a subpanel with 2-pole, 20A AFCIs in it
using individual &quot;spa box&quot; sized panels with GFCI breakers in them (you can even use actual spa panels for this) as subpanels off 2-pole, 20A AFCIs
or using a single large box to mount several unit mount GFCI breakers individually fed from 2-pole, 20A AFCIs in the panel.

The first approach is the simplest and cleanest to implement using &quot;conventional&quot; parts, but has the downside that a GFCI trip takes out all the kitchen receptacles.  The second and third approaches avoid this, but at the cost of either multiplying boxes at the panel or using harder-to-get boxes and breakers (Eaton (QCGFT) and GE (THQC...GFT) make lug-lug/unit-mount GFCI breakers, but they're not exactly home-store items, and you'd need a cutout box and brackets to mount them in/with, too).
Given that, it's probably simpler to have a conduit run out to your kitchen receptacles, so you can pull in extra wires for 240V outlets (which don't need AFCI protection), more circuits, or what-have-you.  This doesn't have to be terribly expensive, either, as it can be done using ENT (&quot;smurf tube&quot;) since that's a mains-legal wiring method in most places that aren't Chicagoland (where you're already using conduit to begin with) or NYC.