Hi,
vo2max sessions are so little fun for me personally on the bike that I very rarely do them.
Have you had any experience with other sports? It shouldn’t really matter whether I train Vo2Max on the bike or in any other way.
I think that rowing or running, for example, would also be very suitable. That would bring some variation into the training.
I’ve looked into this a bit as a runner and cyclist. The consensus is the activity does very little to actually influence your real vo2 max though help you perform better at that sport in that condition.
Obviously there is a physiological improvement as well, though it’s suggested to train in the discipline you plan to compete. That said, doing any vo2 work is better than none, so do whatever floats your boat.
Again - I’ve done ver generic reading on the topic and invite discussion and would love to be wrong here.
XC skiing.
Even though my volume is lower and training totally different, I always feel 7-10 days off the bike but XC instead gives a boost to my cycling.
There’s a theory that because it engages more muscle mass it’s easier to get to (and maintain) VO2 Max when doing this when than cycling.
You’re spreading the load across more of your musculature, I guess.
No idea if there’s validity to the theory, but it sounds plausible, at least.
It’s not just a theory, more muscles used means better venous return to the heart which leads to stroke volume gains.
Still concentrating on your main sport will give you the best gains for that sport.
There’s also the fact (or is it a theory 
) that the hip angle in the standard cycling position puts a cap on venous return.
It seems there’s a vaguely sensible argument for XC skiing (or something similar) to develop VO2 Max during build phases and then using/honing it during race prep phases.
Of course, you’ve got to be good enough at XC skiing (or whatever) to get the potential benefits. If your coordination is so poor or your upper body is so weak that you can’t get your HR over 140bpm it ain’t gonna do much. 
FWIW, i have tried to estimate VO2max using cycling 5-min and rowing 2000m, it is ~10% higher with rowing, although did not achieve nearly as high HR compared to cycling. This is likely due rowing movement recovery phase.
What it means, if anything, I don’t know 
If you’re looking to change it up, I’d recommend running! 
It’s really easy to get into that VO2 state while running, and it definitely uses more muscles than cycling. I’ve found that incorporating running into my routine (often times I’m running more than cycling these days) makes me feel a lot more durable overall.
Just be careful if you’re not normally much of a runner. You need to ease into things and running at VO2 pace can be a bit dangerous in terms of picking up an injury. Make sure you warm up first and build up time in zone slowly!