Can make large difference to strength. As above I use trainer road. Zwift and trainer road in the winter. Tacx vortex here. Mines setup permanently with road bike next to computer. Use BBC Iplayer and sufferfest to mix it up.
Permanent setup is easy to just jump on and go. Fan, drink, towel, sweat mat. Training program on and away you go. Summer I just use it to add quality intervals. In the winter I use it a lot more to avoid the bad weather. Quality IMHO is better than quantity especially for MTB. Trainer road has specific MTB training programs.
Don’t stick it in the garage facing a breeze block wall because you will die of boredom;-)
On turbos I started out with a freebie magnetic resistance one for three years. Changing to quality electric resistance turbo was a huge improvement. It controls the resistance, increasing and decreasing it as the plan or video requires. You train hard. In the winter I also MTB to keep my hand in, trail centres local trails etc. That’s still important.