It seems very clear that Thomas, the OP, wants some exercises. And we continue to give him answers to questions yet to be asked.
That may be because this is a yoga board and not a stretching board or a fitness board or a strength training board.
A student of meditation that has convinced themselves that lotus is essential for their path is better advised to examine their motive for meditation. When meditation is done for pretense, when meditation is done to be a part of a group, when meditation is done for its hipness (no pun intended) then its efficacy is significantly diminished and one could argue that the evolution of the practitioner is stymied by the intention.
Anatomically, the body must have opening in the hips in order for a safe lotus position to be achived. Can an unsafe lotus position be achieved. Absolutely. And it’s done in that way many times over. It is quite ironic becasue in that way it is violent doing rather than meditative “allowing” and as such it becomes the anithesis of evolution, growth, transformation.
While I do not consider stilling the mind as meditation I do consider it a requsite for meditation. This stilling can be done in many positions. Padmasana can become a pretense. You do not need an alter, a locked room, a burning candle, a dimly lit cave, a stick of burning Nag Champa, and Krishna Das in the background in order to meditate. Likewise you do not need padmasana.
However, opening the hips can be done with yoga asana (over time and with mindfullness, skill and instruction) but it is not prescribed like an asprin. If it is exercises one wants then use google. If it is Yoga then seek a yoga teacher.