Typical power strip is rated to 3000-4000VA, while a small home UPS could be 650-2200VA. If the power strip is connected with enough devices and electrical equipment, the capacity of the UPS would be already exceeded. If really required, we can only recommend that the total VA does not exceed what the UPS can deliver. An additional hint or recommendation would be to connect the UPS to the power strip and not the way around. Typical power strips already have a higher surge protection as the UPS, and are way cheaper. This way, the power strip will protect the UPS first, and then the UPS the connected critical loads. Nevertheless, it would function, so there is no serious danger considered.