The obvious solution to me would be to fly it QNH using the altitudes from the FMS which can be cross-checked with the chart, rounding cleared altitudes to the nearest 100ft. QFE only procedures are becoming less common but we used to do this all the time.

Even if changing FMS approach procedures is not prohibited outright, it's not a good idea as it increases the chance of errors manifold. Sooner or later someone is going to flip a number and cross a fix 900ft too low. Some A/C don't even allow tinkering with STARs and approaches.

A relative of Graham McFadden, perhaps? :}

The Russian Federation has decided to adopt the new QNH flight performance standards!

February 13, 2017
Since August 2016, the Federal Air Transport Agency, together with the Federal State Unitary Enterprise “State ATM Corporation” (a subsidiary of the North-West Air Navigation Department), have begun work on the transition to the new system. From February 2, 2017, the crews of Russian and foreign aircraft arriving and departing from St. Petersburg Pulkovo Airport, switched to the new QNH flight performance standards for Russia - flying at atmospheric pressure, the values ​​of which are given to mean sea level .

https://www.favt.ru/novosti-novosti/?id=3288